Troubleshooting Mozilla Thunderbird Outgoing E-Mail Problems

Outgoing e-mail problems can sometimes be more difficult to troubleshoot than incoming e-mail problems. Troubleshooting these types of problems in Mozilla’s Thunderbird is fairly easy if you understand how outbound e-mail works.

Outbound e-mail uses a process called SMTP (simple mail transport protocol). SMTP is the standard for e-mail transmissions across the Internet. SMTP is generally used to send messages from a mail client (Thunderbird) to a mail server. The e-mail is stored on the server until retrieved by another e-mail client using a POP3 or IMAP retrieval protocol.

Outbound e-mail problems can be frustrating to deal with because you rarely see an indicator as to what might be causing the problem. However, there are fewer factors involved when setting up the SMTP section in Thunderbird, so isolating the problem can be much simpler. Unlike setting up an e-mail retrieval for inbound e-mail, with SMTP, a single SMTP setup can be used to cover all of your e-mail addresses, regardless of how many different ISPs are involved. Most SMTP mail servers are set up to allow e-mail accounts from other ISPs to be run through them. Thunderbird identifies the first SMTP account that you set up as being the default account. That is because in most cases it can be shared by all of your e-mail accounts.

Most of the configuration issues with sending e-mail can be resolved in the Server Settings section in Thunderbird.

  1. Select Account Settings from the Tools menu.
  2. Scroll down to the bottom of the list if e-mail accounts.
  3. Select Outgoing Server (SMTP).

The section that you want is at the top of the right-hand side.

Highlight an SMTP account and click the Edit button. The SMTP Server dialog box will pop up.

The Description is not important, but you can certainly enter a description to differentiate SMTP accounts. The Server Name and the User Name are the two important areas to focus on. You will need to get this information from your hosting company or ISP. The account name is usually just the primary account name from your ISP. That is the name to the left of the @ in your primary e-mail address.

When you are sure that this information is correct, click the OK button, shut down Thunderbird and then start it up again to make sure that any new settings are loaded. If you have multiple e-mail accounts and you know that inbound e-mail is working, try sending a test message to another of your e-mail addresses. If it still does not work or you see an error, make sure that you Internet access is active. If you can access the Internet using your browser, you should be able to send e-mail messages once the SMTP information is correct.

If you are still having trouble connecting to the SMTP server, Thunderbird will usually display a message, but depending on the type of error, sometimes it does not. Most of the time the User Name is just the account name, but some configurations may require a complete e-mail address. If one way does not work, try the other.

If your SMTP server requires a secure connection, you may have to check the SSL box. I sometimes use the SMTP server at my AT&T account. AT&T connections usually require that you check the SSL box.

If you are having connections problems, post your issues in the Comments below. Try to give us as much information as you can and we will see if we can help you to get connected. 😉

I have been receiving dozens of questions per week from people who are experiencing the same issues with SMTP server connections for outgoing e-mail with Thunderbird. The problems seem to start without warning. For the first time, I experienced the same issue.

I have three SMTP server connections set up in Thunderbird. The only one that worked is my AT&T account, which uses a secure connection. I went into the SMTP server configuration described above and selected the SSL radio button for one of the two non-functioning SMTP server accounts and clicked OK. Guess what? The connection now works.

Try doing this if you are having problems with outgoing e-mail with Thunderbird and let us know if it works. You may be asked to re-enter your password when you send your first message.

Why did this work? At this point I don’t have a clue because the SMTP server that I changed to use an SSL connection does not use SSL for e-mail.

If this resolves your outgoing e-mail problems, you may also have to change the incoming e-mail setting to SSL under the Server Settings for each e-mail account.


I have now experienced the problem that has been tormenting so many of you, but I still do not know the root cause of the problem. The morning after I made the changes to the SMTP configurations to enable SSL, I changed the setting back to their original state and everything is working fine. Go figure.

So was Thunderbird the cause or did something else happen on my PC or the Internet? I find it hard to believe that two SMTP servers would experience the same problem, but nothing else on my PC or my internal network changed. The only thing that did change is that I upgraded to version (20080708) after I experienced the problem. Thunderbird was working correctly after I booted the PC in the morning. You might want to try doing the update and then reboot your PC to make sure that everything refreshes. Just select “Check for updates” under the Help menu.

Let us know if it works for you.


Important Note #3
If you are using Symantec’s Norton products and either incoming or outgoing e-mail mysteriously ceases to function with Thunderbird, try rebooting your PC to see if that resolves the issue. See Norton May Be Disabling E-Mail for more information.


  1. TE says

    Hi William

    You are not giving me very much information to work with. :o)

    What type of messages are you seeing when you try to send outgoing mail? If Thunderbird does not connect to your SMTP server, it usually gives you a message.

    I’ve just added some additional tips to the tutorial.

    Hope that helps.

  2. Jane Brown says

    I’m having the same problem. Message is ‘connecting to smtp server failed, server may be unavailable or refusing smtp connections. This started only 4 days ago – prior to that all was well. Incoming is ok. Outgoing problem is intermittent, although successful outgoing appears to take longer to connect. I’ve disconnected firewall, etc., but problem remains. Did all your suggestions but problem remains. One blog on internet referred to smtp server memory limit. Is this an issue, and if so, where do I get this info? This is sooooo frustrating! Thanks

  3. TE says

    SMTP problems can be difficult to diagnose if you don’t have any specifications for the proper connection.

    The SMTP server is located at your ISP. You will need to contact them to find out how to make the correct SMTP connection. Most ISPs post this information in a Help section on their web site. For others, you have to call them to get the information. Contacting the ISP will take the guesswork out of this.

    ISPs sometimes change their mailserver configurations. If the problem just started and you have not made any recent changes, I’ll bet that your ISP changed something. I use two ISPs and have seen this happen with both of them.

    Also, unless you are running your own SMTP mailserver, the best way to find out about memory limits is to contact your ISP. If you run a web site and are using the hosting company’s SMTP server, you need to contact the hosting company. Personally, I don’t think the problem has anything to do with the memory limit on the SMTP server. That should only be an issue if a lot of users were sending huge e-mails or the server was getting inundated with traffic.

  4. Amanda says

    I am having problems as well with my outgoing mail. when i send it, it goes to my drafts instead of to the desired recipient. Can you help?

  5. Dorothy says

    I have Thunderbird for my email. I cannot send email messages. Get message-cannot connect to server. Was fine yesterday morning, then not fine. Can do everything else on computer except send emails.

  6. TE says

    You guys need to contact your ISPs or check their web sites to get the current settings for connecting to their e-mail server. ISPs change configuration settings without warning. I have my own mail server and I also use Cox and AT&T as ISPs. Both Cox and AT&T have changed their mail server configurations over the past two years and I’ve had to change the settings.

    I also periodically see the Cox e-mail server go down for periods of time. I have multiple SMTP servers configured in Thunderbird so that I can switch to another if one goes down.

    There isn’t any way to troubleshoot these problems without more information. The easiest way to deal with the issue is to contact your ISP and get the correct settings.

  7. Michael says

    I use yahoo as my server and had the same problem with outgoing email. When I changed the settings on the outgoing mail to an ssl secure connection on port 465 my outgoing mail starting working.

  8. TE says

    Several ISPs have gone to secure connections. When you click the SSL radio button, the port should automatically change in Thunderbird.

  9. Renee says

    My out going just stopped working this morning.
    the message is “Sending of message failed the message could not be sent because connecting to SMTP server failed. The server may be unavailable or is refusing SMTP connections. Please verify that your smtp server setting is correct and try again, or else contact your network administrator”
    I haven’t changed anything in the last 24 hours?????
    Any suggestions?

    Rogers told me it must me Mozilla!

  10. TE says

    Hi Renee

    It looks like there is some finger pointing going on. I think the message sums it up. Every time I have seen this happen, the problem was with the ISP changing their mail server configuration. It is possible that it could be a Windows issue if you updated or changed firewall software configurations, but the message points to a problem with the ISP.

    I have never seen Thunderbird just stop working. Try changing some of the configurations I mentioned above to see if you can find the correct combination.

  11. harry hayward says

    hi, i can send and receive mail via the default account, and receive from my other two accounts. my two secondary accounts will not send. error states, from address not verified. any help please

  12. TE says

    If the other two accounts are Yahoo accounts, the problem is with Yahoo. Do a Google search for “thunderbird address not verified” and you will see a ton of information about problems with Yahoo accounts generating this message.

  13. Nick says

    I am using Thunderbird with AT&T Email and I am having problems sending email. I can receive email fine, I can not send email. I have been on the phone with AT&T and they only have support for older versions of Thunderbird. They don’t even know how to fix it. I have all the SSL settings and POP3 as well as the proper SMTP settings and I still get an error message when I go to send an email. Does anyone have any ideas on what this could be?


  14. TE says

    Hi Nick

    My AT&T account uses a slightly different configuration than other ISP accounts. Here is how my SMTP is configured for AT&T. See if yours is set up the same.

    Server Name:
    Use Name & Password: (checked)
    User Name: (use your primary account)
    SSL: (checked)
    Port: 465 (changes when you check SSL)

    Make sure that you use the ‘i’ at the beginning of the AT&T server name. They changed that a while ago.

    Also, make sure that you have the AT&T SMTP account selected on the Account Settings page. Thunderbird allows you to set up multiple SMTP accounts and it is easy to forget to select the right one.

  15. JC says

    I had this same problem — outgoing email spontaneously stopped working, except at Tbird startup. Solved it by going to Accounts, Outgoing Server, Edit and making sure my username was on each outgoing server info and either checking SSL or its opposite. Seems to have worked itself out. Hopefully. Thanks for the tips/info herein.

  16. Joachim says


    I have just installed Thunderbird and set things up. Earlier this evening everything worked fine. Now all of a sudden I get the same SMTP error message others here have mentioned. But the thing is – I *know* that it’s neither a problem with my ISP or wrong settings for the account. The reason I know this is because I had both Apple Mail and Thunderbird open at the same time in order to test if it was an ISP issue. I had written the same email message in both applications and tried sending it from Apple Mail first – which worked fine. I then immediately tried sending from the same account with Thunderbird, but it just gave me that same old SMTP error message. I have quadruple-checked that the settings for the account are the same in both applications. And by the way, the email server is running on my own VPS server, so I *know* there’s not a problem there either. This means there is definitely a problem with Thunderbird.

    Anyone here happen to know a solution for this apparent bug?


  17. TE says

    It does seem like a lot of people are having similar problems. But I’m still not sure that it is a Thunderbird problem–although it could be.

    Here are some questions to ask to try to pinpoint the source of the problem. Software bugs do not occur spontaneously. In the case of systems like this, it is usually due to a software update. But because of the complexity of the Windows operating system, the problem could be due to interaction with another system.

    1. Just prior to the problems occurring, did Thunderbird inform you of an update? These updates do not occur automatically. A message does display when an update is available.
    2. Did a Windows update occur just prior to onset of the problem? Windows does sometimes automatically install updates without your permission. I could write a very large book about various problems associated with Windows updates.
    3. What type of anti-virus software are you using? Norton updates occur at least weekly. I’ve seen several problems with Norton updates. Most of them are fixed with the next update.
    4. If you are using a software firewall, did an update occur just prior to the problem? A firewall can block the connection to your ISP’s server.

    Any of these systems can be the root of the problem. You can always try to temporarily disable a firewall or antivirus program to see if that fixes the problem

    I have personally seen this same issue many times over the past few years, and from my experience, it has always been an ISP issue, but I am not ruling out other possibilities.

    Joe, your test is valid and if the settings were identical, should rule out an ISP problem, but it doesn’t rule out a problem related to some other Windows system that interacts with Thunderbird. Try looking at some of the systems I identified that interact with Thunderbird.

    We also need to look at which version of Thunderbird people are using. As of 3/24/2008, the most current version is build 20080213. You can find this information under Help, About Mozilla Thunderbird. There is also a link to check for updates. Make sure that your version of Thunderbird is current.

    Let’s see if we can narrow this thing down and find out what is causing the problem. When software works for a period of time and then just stops working, something has changed somewhere.

  18. Joachim says

    Hi, thanks for the detailed reply. Well, it’s certainly not a Windows problem, as I’m using a Mac with OS X 10.5.2 :) And there was no OS X update in between the app working and breaking.

    Aslo, I can’t see it being a Firewall issue, since it worked fine in Apple Mail 1 second before trying with Thunderbird.

    I don’t have any anti-virus software installed either, so that’s not it.

    I’m using the latest Thunderbird version and build.

  19. Cheryl says

    We are having a similar problem. When trying to send an email we get the following:
    The message could not be sent because connecting to SMTP server failed. The server may be unavailable or is refusing SMTP conncetions. Please verify that your SMTP server setting is correct and try again, or else contact your network administrator.

    Unfortunately, the email does indeed send, it just will not place a copy in the persons local email folder. It doesn’t matter if the sent folder is on the email server, the local hard drive, or our network server. It doesn’t happen everytime, and it doesn’t seem to matter what version of thunderbird we are using. It isn’t happening to everyone either. So far it seems that the people who are reporting the problem all had it start sometime in January. We have tried upgrading thunderbird, removing ssl, changing local folder locations, removing thunderbird completely, reinstalling, making the person an admin on their machine, ran wireshark (it didn’t show any errors). Any ideas?

  20. TE says

    I honestly do not know what the issue is here. Obviously, lots of people are experiencling problems, but the limited information that Thunderbird offers doesn’t tell us much.

    We are running Thunderbird on about 10 PCs and we have not had a single problem with either our ISPs or with Thunderbird for the last six months.

    If the problems started in January, something changed in January. The trick is to figure out what changed.

    Has anyone found a fix for this issue? If so, please post it.

  21. TE says

    Good find, Gregg!

    That looks like the resolution to the Yahoo problem that I mentioned earlier.

  22. Dirk says

    Hi All,

    Similar T-Bird issues here.

    My wifes Tbird started “eating” her outgoing emails about 2 months ago, which may be a separate issue.

    And my email client (Tbird) decided to stop sending mail last night.

    I’m a so called “power user” and I’ve checked everything several times over, and no solutions presented.

    I wonder if it’s connected to the NSA’s “secret room” in San Francisco mucking up our emails!

  23. TE says

    Hi Dirk

    The secret room theory is a possibility. :)

    If you have not made any other changes to your PC, this looks like a classic case of ISP problems. You may find that it is working today. If not, call tech support at your ISP.

    BTW, I started a new post with typical SMTP configurations. You can see it at SMTP Configuration Scenarios.

  24. deb says

    I just started having the e-mail problem with ATT. I went thru the steps they give, got a verification code, still didn’t work. Called Tech Support, they told me, yes, my settings were correct. Move “higher up” Tech says they don’t support Thunderbird, (even tho they’re website says they do) but I can use their Paid Support service if I would like and “see if they can help.” Yeah, right. Are they planning to support T-Bird in the future? Dunno. Nobody knows nuthin’. Sorry to have to go on to something else. Hope they will fix this.

  25. Charles says

    My problem is that it tells me the message was sent, and it places a copy as I want it to in the sent mail folder, but then sometimes the message isn’t sent (but sometimes it is). This happens with both my university account and my Gmail, so I’m not sure what is going on.

  26. TE says

    Hi Deb

    Aren’t large companies just a joy to work with?

    You might want to try clearing your Thunderbird password and re-entering it when requested. Check out Changing Thunderbird Password. If the password is incorrect, you won’t get anywhere, even if the other settings are correct.

    Hi Charles

    You are not giving me much information, but your issue could be related to a virus or spam filter that is filtering outgoing e-mail messages. You might want to try temporarily disabling your virus checker, or looking for a way to disable the filtering of outgoing messages. Some anti-virus software only checks incoming messages, while others check outgoing, as well.

  27. laco says

    i’ve been having the same problem for two weeks now. T-bird just stopped sending emails all of a sudden. The error message says T-bird couldn’t establish smtp connection with the smtp server etc….. I have configured several accounts with different smtp servers…none of them work and they are set up correctly. Recieving emails is OK. Sending via webmail works correctly.

    One more issue. The first thing that occured was an error message saying that a page called was blocking outgoing emails. This happend to most of my friends. We went through a removal proces at that webpage, where you had to have your IP removed from some kind of a IP-spam-list or whatsoever. And after this i am getting the above mentioned error message. Wondering if there is a connection between these problems or if any of you have experienced this. Thanks for the reply

  28. TE says

    Hi laco

    That’s a good point. It could be the problem for several users, but no one else has thus far reported the Spamhaus (it is message. This would point to a problem with your hosting company or ISP who is using this freebie service.

    Wikipedia has a good article called The Spamhaus Project.

    Spamhaus blocks e-mails that it determines to be spam. It is possible that it is malfunctioning or a number of IPs were just added to the block lists that it uses.

    I’ve been working with software for over 20 years. It just doesn’t break or stop functioning unless something changes. The real problem is trying to find out what has changed when there are so many interactions with other systems on a PC, an ISP, a hosting company, the recipient’s PC, etc.

  29. David says

    Hi TE,

    I realised T-Bird was not working properly when it failed to ask for a password on opening. I started testing to see if I could still receive and send emails. I would send emails from T-Bird to my Hotmail account and send emails from Hotmail to my T-Bird accounts. I have found out that I am not receiving emails and only the odd email will send. I get no warnings pop up at all.

    I have, in the last few days, changed my anti virus software to ESET. I checked all settings, even disabled the av and firewall but still have the problem.
    I updated T-Bird to the latest, still no fix!

    I think I must have gone over every setting, checking, double checking and still T-Bird will not work.

    Help would be very much appreciated!

  30. Todd says

    My out going just stopped working this afternoon.
    the message is “Sending of message failed the message could not be sent because connecting to SMTP server failed. The server may be unavailable or is refusing SMTP connections. Please verify that your smtp server setting is correct and try again, or else contact your network administrator”

    I have contacted my isp provider and the tel me that they haven’t reset the smtp settings, This happened out of the blue, i sent one email the next about 5 minutes later and it started with the above message. Ive even tried an alternative smtp setting which my provider uses, but to no avail can you help ?

  31. TE says

    This message is to everyone looking for relief from problems with outgoing mail with Thunderbird. I am getting deluged with requests for help and I cannot post everyone’s issues, especially when most are just a general description that does not really tell us much about the root of the real problem. Unfortunately, there isn’t enough time in the day to assist everyone with these issues. We have to do it through this blog.

    The problem is that trying to troubleshoot e-mail problems remotely is like the story of the four blind men trying to describe an elephant. None can actually see it and therefore each envision as something quite different. E-mail error messages are usually vague and frequently do not tell us anything about the real root of the problem.

    E-mail clients work with multiple systems: your PC’s operating system, your anti-virus software, your firewall (if you have one), your ISP’s mailserver, anti-spam systems, etc. Connection problems can be due to any failure or change in any part of the system or chain of events. It is not necessarily due to Thunderbird, although the most visible symptom is that Thunderbird stops working.

    I’ve been working with software for many years and I have never seen a working software system just cease working unless something changed somewhere. The most likely places to find changes that affect connections are either in your PC or with your ISP. From my experience, the ISP is at fault the vast majority of the time. We also see ISPs frequently deny that there is a problem. Sometimes they just need to reboot their mailservers, but only do so after receiving numerous complaints.

    The best advice that I can give you if you are having outgoing e-mail problems with Thunderbird is to read through this post and the one on SMTP Configuration Scenarios and try making the changes to see if that helps.

    Do not panic if your e-mail stops working. I see our e-mail connections temporarily stop working sometimes a couple of times per month. The problem that I see is always with the ISPs. Their systems start working again if I simply wait an hour and try again.

    If you do find a solution to your e-mail problem, please post it here so that others might find a resolution to their problems. :)

  32. Tim says

    First; I setup the outgoing mail server, mail.tomain.tld, checked user name and password, left user name blank. Clicked ok, closed thunderbird. Opened Thunderbird, created a test message and…
    Relay access denied, never prompted for a user name or password.

    Second; I setup the outgoing mail server, mail.tomain.tld, checked user name and password, added user name. Clicked ok, closed thunderbird. Opened Thunderbird, created a test message and…
    Relay access denied, never prompted for a password.

    Went to Outlook, clicked my server requires authentication and use the same account as the pop3 account. Sends just fine.

    I can reproduce this on two systems connecting to a postfix server running clear text authentication.

  33. TE says

    Hi Tim

    You are not getting asked for a password because that request comes after the initial connection to the mailserver. It looks like you are not connecting to the mailserver.

    Why are you leaving the user name blank? That is a critical part of the authentication process. If you don’t give it a user name, the mailserver may not know which account to try to connect to.

  34. Hiten says


    I am using Thuderbird 2.0 version from last one month, and it was working fine. But from last two days when i try to send email, it gives message like “Sending Message Failed. The message could not be send because connecting to SMTP server ‘’ failed. The server may be unavailable or its refusing SMTP connections. Plase verfiy your SMTP server settings, or else contact network Admin person”. I have checked settings with network ppl, and settings are fine. Just facing error with send, i can receive message on same email id!! PLEASE HELP

    This problem is facing by many of our company person but its working fine with many of.

  35. Joe says

    SMTP failed. It has been working fine until today. There was no recent update. Here’s my error message: “An error occurred while sending email. The mail server responded: User not local; please try . Please check the message recipients and try again.”

    Message recipient addresses are not the problem–I checked and rechecked.
    Thanks for looking at this issue.


  36. ashley says


    My email is a work email. When I go to work, like this morning I was able to send emails. As soon as I get home I am unable to send email. It says the following:
    The message could not be sent because connection to the smtp server failed. The server may be unavailable or is refusing the smtp connections. Please verify the your SMTP server setting is correct and try again, or else contact your network administrator.

    Can someone explain why I can receive emails at home on Thunderbird, but can’t send outgoing messages

  37. TE says

    Hi Ashley

    Sending and receiving e-mail are two very different operations that function differently. There is obviously a problem with your connection to the SMTP server, which handles outgoing e-mail.

    It is frequently not possible to determine what the problem is based upon the messages Thunderbird displays. SMTP server connections are one of the most common problems. There are dozens of possible reasons as to why the connection is failing. Make sure you are using the proper connection settings. ISPs sometimes change these settings. Also, try the tips on this page to see if it starts to work.

    There was a Microsoft update a few weeks ago that I think screwed up some Thunderbird applications. My version of Thunderbird still works, but both it and Internet Explorer started to function differently immediately after the Microsoft update. Since then, I get a dozen messages per day from people who say that Thunderbird no longer works. I don’t yet have the answer for this, but highly recommend that people use the Check for Updates tool under the Help menu.

    The problems that I see that people frequently have with Thunderbird have nothing to do with Thunderbird, but are due to something else that has changed on their PC, network or ISP.

  38. Aline Schäfer says

    I have had a similar problem for the last four days. When trying to send a mail I receive the message that I should check my account settings. Although I haven’t changed the settings since setting up Tbird two years ago, I have checked all the settings, deactivated my firewall, but nothing helps. Should I try a system reset?

  39. TE says

    See the information in the boxes above marked Important Note #1 and Important Note #2 and let us know if it resolves your outgoing e-mail issues with Thunderbird.

  40. Aline Schäfer says

    no yellow box? Have just downloaded the newest update but still no success.

  41. Aline Schäfer says

    Hurrah! Clicking the sll radio button actually worked! Brilliant, thank you millions.

  42. K. Ghosh says

    My Thunderbird is sending out mails but they are all bouncing back after one hour with the message –

    Thu 2008-08-21 09:54:23: Attempting MX: P=010 TTL=(54) MX=[] {}
    Thu 2008-08-21 09:54:23: Attempting SMTP connection to [ : 25]
    Thu 2008-08-21 09:54:23: Waiting for socket connection…
    Thu 2008-08-21 09:54:24: Winsock Error 10061 The other host is either down or has refused to connect with you at that IP and/or on that port.

    I have been facing this problem for a week now and with Thunderbird alone (tried the SSL also, no joy). Prior to this week things were absolutely fine. Also, the same smtp settings work fine for Sylpheed and Sylpheed Claws from the same computer; mails sent to gmail/yahoo are accepted without complains.

    I have updated to the latest TB – version (20080708), but this has not helped. I am on Win-XP.

    Can someone please help.
    Thanks in advance,

  43. TE says

    Hi K.Gosh

    Your problem is a bit different than others because the messages are going out, but are then bouncing back. It looks like your messages could be getting blocked by a firewall or a mailserver. You could be getting tagged as a spammer. Are you sending out lots of messages? It is possible that your IP address is on a spam blocklist.

    Also, some SMTP servers refuse to forward e-mails if you have too many recipients. That will be a problem if you are trying to do that through gmail or if you are sending too many messages to gmail accounts. AOL and others also block excessive e-mails coming from a single IP.

    If you can, try changing to a different SMTP server and send a message to a single recipient. See if that gets through. You can also try resetting your IP address through your ISP.

    Still, that doesn’t explain why the messages are getting through with Sylpheed. I’m beginning to wonder if there is something on the web that is messing with messages from Thunderbird. :(

  44. Thunderbop says

    I had a problem with Tbird today: it would not send email. I tried a warm reboot of my computer and had no luck. But a *cold* reboot of my computer solved the problem.

  45. K. Ghosh says

    Since this is my office computer, I could not hold out without outgoing mails. I have now switched over to Outlook Express and things are fine. But it is really a mystery why TB borked.

    We have two servers through which all of us access and send mails, one for internal mails and the other for external mails (only some of us have the privilege of sending external mails). The mails I was sending were all test mails without any attachment and sending to myself at my gmail and yahoo ids, with no copies. since I alone was using TB, I cannot say if others had the same problem.

    I think you may have a point there about some sort of sabotage on the web for messages from TB. How to verify this ?


  46. TE says

    My thoughts are that there is something external to Thunderbird that is causing this. It happened to me for one day.

    There are many, many possible variables that could cause the problem due to the interactions of Thunderbird with a lot of different programs and systems.

    I do not yet have the answer, but perhaps someone will figure it out and post their ideas here.

  47. Greg says

    This is weird.

    I use Comcast.

    I have not been able to send mail, but could receive mail.

    I went to Server Settings and changed the port to 587. Previously it was 110. 587 is the setting advised by Comcast for Outgoing Mail. 110 is the setting advised by Comcast for Incoming Mail.

    Now I can send mail!

    But I cannot receive mail!!

    I guess I have to choose between sending and receiving:)

    Comcast support does not support Thunderbird. I believe they did in the past.

    Any advice?

    Thanks for the instructions on this page. They are the clearest I have found.

    Thank you.


  48. Greg says

    I figured it out. (See my comment at September 1st, 2008 at 4:44 pm.)

    I left the Outgoing Server (Smtp) Port setting at 587.

    I changed the — Server Settings — Port back to 110.

    Now I can send and receive mail!


    Thanks again for providing this page. I hope my experience can be helpful to another user.


  49. Vickie says

    I have Comcast email, as well. We hired a tech company to help with various computer issues. He couldn’t figure out why were were having problems sending email! He said we couldn’t use Thunderbird on this computer. But we had been using TB, so that didn’t make sense. But thanks to your site, I — a non-techie person — solved the problem. I had to select the “SSL” Secure Connection and the following:
    POP Server – port 995
    Outgoing server – port 465

  50. Cathy says

    Each time I log on to my in box for thunder bird a drop box in the middle of the screen says,failed to connect to server . At the same time get message in the lower left hand corner that tells me I am connected , which I am. Deleting the failed connection alert each time. Why is this popping up and how do i fix it?

    My email domain is using google apps- hence the
    As with all gmail settings i have to use port 995 w/ssl checked.

    Thanks for any light you can shed.


  51. TE says

    Hi Cathy

    I do not use GMail and have never seen the problem you are experiencing. Perhaps somone will have a solution for you.

  52. Dave says

    My issue was a little different as the connection was being refused. I just used the settings that Vickie provided: 995 w/ SSL checked and 465 on the outgoing server and had success.


  53. Deb says

    I’m having the same problem many have mentioned.

    I can’t send out using my SECONDARY accounts. My primary account works fine. All are accounts, all were set up 5 years within minutes of one an other.

    I ran Outlook 2003 for the majority of the time, but found it too old to work well with Vista when I got my new computer last week. I downloaded the current version of Thunderbird and it cleared up the “old” problems I was having with Outlook, but it continues the same problem of not being able to send from SECONDARY accounts.

    So I was having this same problem with Outlook 2003. I thought that indicated the problem was with ATT, but I just spent a frustrating hour verifying that no, it wasn’t. I even tried adding a brand new subaccount on the theory that something about the old account was lacking something. Still got the same non-connect/not verified message.

    I’ve attempted everything suggested above. I’m at a loss.

  54. Doogie says

    Hi Deb

    The fact that you are having the same problem with Outlook just verifies that your configuration is very likely the problem.

    If you are using AT&T, make sure that you have SSL selected. Check out the SMTP Configuration Scenarios. There is an AT&T setup shown there.

    When you make a change in Thunderbird, be sure to restart Thunderbird to assure that the change takes effect.

  55. Deb says

    No, it’s not the configuration. I 1) know what I’m doing with that and 2) spent literally over an hour on the phone with AT&T trying to get it straightened out, so if I had missed anything, they would have caught it.

    I’d be thrilled if it were that, but it simply isn’t the problem. Heck, I even said the same thing about both programs having problems being proof something had to be there, but apparently not.

    Could the similarities in the two programs be the problem? At least on the surface, Thunderbird seems closely modeled after Outlook. If it is, then couldn’t a weakness as well as the strengths in Outlook have also been programed into Thunderbird?

    I’ve been sticking with T-bird because I like it, but if the problem isn’t being worked on, then I’d like to know so I can start trying different programs.

    Thank you!

  56. Doogie says

    Hi Deb

    Thanks for the feedback.

    Don’t rule out a configuration problem, even if you are experienced with e-mail clients. A good troubleshooter never rules out any possibility.

    The most common response from ISPs is that they are not causing the problem, but they frequently are the problem. I get denials from Cox every time I call them with an issue, but thus far it always turns out to be their problem. I just have to push hard enough to get them to take it seriously.

    If you are having problems with both Thunderbird and Outlook, you basically have two possibilities: 1) configuration issues or 2) something is blocking the connection, such as a firewall.

    I have not heard of any conflicts between Thunderbird and Outlook, but something else on your PC could be preventing both from operating properly.

    The questions is who should be working on the problem? There isn’t any easy fix because there could be dozens of reasons for connection problems and e-mail clients do not give enough information to pinpoint a problem. We have seen all kinds of issues in this post that had different resolutions. You just have to keep pecking at the problem until you find something that works.

    Thunderbird is a free software product developed by volunteers. If the problem is program-related (which I doubt based upon what we have seen), then we have to wait until someone on their team finds an answer.

    Try another freebie program, such as Eudora, and see if that resolves your issues. If it doesn’t, you will know for certain that the problem is either a configuration issue or something blocking the connection.

  57. James Moxham says

    I think Greg (Sept 1st) may have solved this.

    In summary, new install of thunderbird, imported all the settings from outlook express, incoming works, outgoing doesn’t work, firewall off, virus programs off. Outlook express settings identical to thunderbird settings.

    Read through all the posts. Tried everything. But to summarise, just change one setting as Greg says – change the outgoing port from 25 to 587.

    I wonder if this solution could go to the top of the page?

  58. cas says

    Hi-i recently swapped from toucan to talk talk and ever since, my incoming email is fine, but my outgoing fails with the following message
    ‘An error occurred while sending mail. The mail server responded: relaying to prohibited by administrator (failed to find host name from IP address) Please veify that your email address is correct in your Mail preferences and try again.’
    i havnt changed anything else and am still using thunderbird – any suggestions, thanks

  59. Doogie says

    Hi cas

    I’m not familiar with either of those services, but it looks like Talk Talk verifies the host name and is failing to do so. It doesn’t look like a Thunderbird problem.

    You might want to see if there is a way to turn the host verification off in your Talk Talk account.

  60. Chris says

    I have an interesting problem, which I have not seen discussed anywhere. When I send an outgoing mail, Thunderbird takes forever and usually times out. This does not happen every time, but a majority of the time. If I cancel the sending immediately and then hit send again, the email goes right through! The second send always works with no delay. It seems to be a strange problem, and I have searched extensively for an answer. Anyone?

  61. Victor says

    I was having the same “sudden” smtp problems as many others are having…but after switching the setting to ssl, everything works fine. Go figure, my server doesn’t use ssl, and until today, no encryption was working great. Oh well…just thought I would throw in a success story.

  62. Christine says

    I have just started to get an smtp error as above using TB. I was able to get Outlook working so I don’t think my settings are at fault. I have no trouble receiving but simply cannot send out. I’m using Rogers to send. Bluehost receives for me.
    I thought that maybe my passwords were bad, so I went and wiped them all and re entered but no go. I reinstalled TB but still no change.
    I have not been messing with my setting but just added a new account. (a new email) I have done this before with no issues. Besides it did not stop working for quite a while. Likely no connection.
    I am getting downright snarky about this!!
    I have had my port set on 587 with no problem till now.
    Talked to Rogers and they confirm my sign in name and password are correct. Its hard to argue that they are at wrong when Outlook connects.

  63. Doogie says

    Hi Christine

    Unfortunately, you have not provided any information that helps to identify the cause of the problem. I can offer two pieces of advice:

    1) Re-read everything on this page and try the different techniques that people have reported that fixed the problem.

    2) Try setting up an SMTP server connection through Bluehost. I am not sure why you are receiving though Bluehost but sending through Rogers. The outgoing problem is likely with Rogers. The vast majority of ISPs deny that the problem is on their end, even after it is proven beyond any doubt to be their problem.

  64. Bob Morris says

    The message I get is” “ssl protocol disabled”. I tried a reinstall, reboots, and checked the firewall which one message suggested is the problem. Just for my own information, I unchecked all the boxes and went with no security encryption. My Thunderbird works without ssl checked…

  65. Doogie says

    Hi Bob

    Not all servers have SSL enabled. Most do not. It is apparently not enabled on your mail server. That means that is is not a Thunderbird issue. If you feel that you need to have encryped e-mail, talk to your ISP or hosting company.

  66. Allison says

    Trying to send out large email (church mailing – 79 addresses). The message appears in “sent” folder, but my test message does not arrive in my in box. I tried sending myself (to my own address alone) a test message, and it went through fine immediately. The send from and send to accounts are different.

  67. Doogie says

    Hi Allison

    We have not been able to determine if there is any limit to the number of recipients with Thunderbird. Other e-mail clients we have used limit you to 10 recipients in a message and so do many ISPs. According to this Thunderbird forum thread, it could also be your virus program. It is most likely your ISP’s SMTP server configuration. This would be the reason for not receiving any warnings messages. The limit on the number of recipients is intended to prevent spam.

    1. Use Thunderbird’s Mailing Lists.
    2. Break up your list into groups of 10 or less.
    3. Try it again. It should work. If it doesn’t, check with your ISP.

  68. Ben O'Sullivan says


    Over the past few weeks the number of failures I have when sending email using Thunderbird has increased to alarming proportions, and it takes on average 10 or 12 attempts to succeed.

    On the majority of these I get a warning that the reason is that my IP address is listed, and this is confirmed on the occasions I have checked.

    I always thought that I had only one IP address, but from these spamhaus messages I have figured out that I have had at least half a dozen or more which now makes me consider that something sinister is going on, and that my email system has in some way been compromised.

    Can you make any suggestions?

  69. Doogie says

    Hi Ben

    This is not a Thunderbird issue.

    Anyone can use your e-mail address. There is nothing that will prevent a spammer from using it. However, your e-mail IP address is assigned to your ISPs mail servers. You may be sharing those IP addresses with thousands of other users. Report the problem to your ISP. If they do not fix the problem, find another ISP.

  70. Ben O'Sullivan says

    Hi Doogie,

    Thanks for the reply and at least you’ve confirmed my suspicions about the majority of my failures, which I’ll now take up with the ISP tomorrow.

    However, the remainder are then just Thunderbird SMTP failures as per most of the posts above. I have done the SSL bit, the “get new mail” before sending, re-checked the addressees and even gone back to an earlier version of Thunderbird, but all to no lasting avail, and hence my dilemma.

  71. dbd says

    Similar Problem – Unable to send mail using Thunderbird v2.0.0.23(20090812) – message pops up as follows:
    “Sending of message failed.
    The message could not be sent because connecting to SMTP server mail.***** failed. The server may be unavailable or is refusing SMTP connections. Please verify that your SMTP server settings are correct and try again, or else contact your server administrator.”

    A range of suggestions have been tried without a cure.

    When deleting and re-saving smtp password the following was noted.
    Under Tools>Options>Privacy>Passwords- ‘Edit Saved Passwords’ in ‘Password Manager’ the entry under ‘Username’ for ’smtp’ states ‘not specified’ while the correct username for ‘mailbox’ IS listed.

    Checking under Tools>Account Settings – ‘Outgoing Server (SMTP)’ the username IS listed.

    Could this mean that Thunderbird is correctly identifying the username for the incoming mail but is attempting to send mail through the ISP server without identifying the username, resulting in the message above?

    If so, is there a setting in Thunderbird>Tools>Options – Advanced – ‘Config Editor’ in the ‘aboutconfig’ window that is relevant to address this (that is, if it is an issue)?

    If this is an issue, what caused Thunderbird to be sending through messages one minute and not the next, during the same session?

    (No account changes were made mid session, no Windows updates/changes were made that day or on days either side. As a check, MS Outlook on another computer was able to receive/send email through same email account, so this appears to be a Thunderbird issue. My preference is to continue using Thunderbird if there is a solution)

  72. Doogie says

    Hi dbd

    The usernames for the SMTP servers in the password viewer in my installation of Thunderbird also say Not Specified, so I do not think that is the problem.

    I cannot explain why Thunderbird works one minute and not the next for a number of people. It occasionally does that for me, as well. However, in my case all indications are that the problem is with the ISPs. Either their mail servers are down or they are too busy. I suspect the real issue with Thunderbird is lack of patience. It appears to stop trying if it does not immediately connect to a mail server. I have also seen Norton Anti-Virus appear to periodically block Thunderbird. Why? Unfortunately, I don’t know. Given the number of viruses and Trojans circulating today, I do not recommend that anyone shut off their virus software just to receive e-mail.