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Suddenly stopped downloading/syncing emails

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Hi, this issue is consistent across all my computers - home, work, laptop.

At some point during the last couple of weeks, Thunderbird has suddenly stopped being able to connect to *some* IMAP mail servers and/or download messages.

No settings have changed, and if I try to delete an account and set it back up again using the new account wizard, it appears to fail verification (username/password) even though they are 100% correct.

I am able to connect OK using a different mail client on my smartphone, and it's only mail accounts on a particular server which fail to connect. I have several other email addresses on another server/host which still connect fine. The server settings are the same (apart from the server address and login info of course).

All that appears in the notification area at the bottom left, is "Checking mail server capabilities".

The accounts are using STARTTLS (port 143), but if I change the security to SSL/TLS (port 993) then it makes no difference. Only if i disable connection security is the connection established and the emails start coming through.

Just to confirm, this has been working fine for 5+ years with the same mail server, no settings have changed from my end, and this literally started happening overnight. Accounts on other mail servers connect fine using the same connection security (which may point to the mail server software no longer being supported or something?)

Please help, not keen on using an insecure connection. Thanks in advance.

Hi, this issue is consistent across all my computers - home, work, laptop. At some point during the last couple of weeks, Thunderbird has suddenly stopped being able to connect to *some* IMAP mail servers and/or download messages. No settings have changed, and if I try to delete an account and set it back up again using the new account wizard, it appears to fail verification (username/password) even though they are 100% correct. I am able to connect OK using a different mail client on my smartphone, and it's only mail accounts on a particular server which fail to connect. I have several other email addresses on another server/host which still connect fine. The server settings are the same (apart from the server address and login info of course). All that appears in the notification area at the bottom left, is "Checking mail server capabilities". The accounts are using STARTTLS (port 143), but if I change the security to SSL/TLS (port 993) then it makes no difference. Only if i disable connection security is the connection established and the emails start coming through. Just to confirm, this has been working fine for 5+ years with the same mail server, no settings have changed from my end, and this literally started happening overnight. Accounts on other mail servers connect fine using the same connection security (which may point to the mail server software no longer being supported or something?) Please help, not keen on using an insecure connection. Thanks in advance.

All Replies (2)

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It sounds to me like security standards have moved forward in the last 5 years and your mail server has not kept pace. Hence disabling connection security working.

SSL is completely obsolete, it has been replaced with TLS. Any SSL certificates less that 2046bit are also history, although removing the 512 bit "US export ciphers" 12 months ago appears to have caused the most angst, 12 or more years after they were obsolete.

What mail provider/server name?

  • Open the error console (Ctrl+Shift+J)
  • Clear it
  • Check for mail.

What is the error message that appears. (Right click to copy errors.)

If you enter the server with the appropriate ports here you will get a report on the server security status with regards to SSL/TLS in general. Most that have issues get an F

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Hi, sorry for the late reply, but thanks for your comments. Seems that something changed so it's started working again - not sure if due to an update in Thunderbird, or an update on the mail server - strange, but at least it's fixed. Thanks again.