Description of problem: TB refuse to download emails from IMAP server. Not really sure what happened. This is the log I get (with newly created profile, just to be sure): ~~~ $ NSPR_LOG_MODULES=imap:5,timestamp thunderbird [calBackendLoader] Using Thunderbird's builtin libical backend 2018-02-22 14:19:40.563905 UTC - 751814400[7f3621d13460]: ImapThreadMainLoop entering [this=21daa000] 2018-02-22 14:19:40.563959 UTC - 1613412160[7f365ed63140]: 21daa000:mail.xxx.com:NA:SetupWithUrl: clearing IMAP_CONNECTION_IS_OPEN 2018-02-22 14:19:40.566009 UTC - 751814400[7f3621d13460]: 21daa000:mail.xxx.com:NA:ProcessCurrentURL: entering 2018-02-22 14:19:40.566109 UTC - 751814400[7f3621d13460]: 21daa000:mail.xxx.com:NA:ProcessCurrentURL:imap://vondruch.com:993/select%3E%5EINBOX: = currentUrl 2018-02-22 14:19:41.072738 UTC - 751814400[7f3621d13460]: ReadNextLine [stream=21c16180 nb=0 needmore=1] 2018-02-22 14:19:41.072793 UTC - 751814400[7f3621d13460]: 21daa000:mail.xxx.com:NA:CreateNewLineFromSocket: clearing IMAP_CONNECTION_IS_OPEN - rv = 805a2f8d 2018-02-22 14:19:41.073045 UTC - 751814400[7f3621d13460]: 21daa000:mail.xxx.com:NA:TellThreadToDie: close socket connection 2018-02-22 14:19:41.073079 UTC - 751814400[7f3621d13460]: 21daa000:mail.xxx.com:NA:CreateNewLineFromSocket: (null) 2018-02-22 14:19:41.079292 UTC - 751814400[7f3621d13460]: 21daa000:mail.xxx.com:NA:ProcessCurrentURL: aborting queued urls 2018-02-22 14:19:41.089575 UTC - 751814400[7f3621d13460]: ImapThreadMainLoop leaving [this=21daa000] ~~~ Version-Release number of selected component (if applicable): $ rpm -q thunderbird thunderbird-52.6.0-2.fc28.x86_64 How reproducible: Steps to Reproduce: 1. 2. 3. Actual results: TB does not download emails nor list of folders, anything. Expected results: TB download mails just fine. Additional info: Yesterday, it used to work just fine. I updated the computer and still, I would say it worked just fine, but today, it does not work. Not sure if it might be server side issue or how to debug it.
Of, finally I discovered that in JS console, there is reported following error: ~~~ An error occurred during a connection to mail.xxx.com:993. SSL received a weak ephemeral Diffie-Hellman key in Server Key Exchange handshake message. Error code: <a id="errorCode" title="SSL_ERROR_WEAK_SERVER_EPHEMERAL_DH_KEY">SSL_ERROR_WEAK_SERVER_EPHEMERAL_DH_KEY</a> ~~~ I was suggested by Jan Hořák to try [1], so I disabled all the "dhe" options and it seems that my TB can connect to the server once again. Not sure if the security is better or worse now though. [1] https://support.mozilla.org/cs/questions/1065417
This seems to be caused by crypto-policies change: https://fedoraproject.org/wiki/Changes/StrongCryptoSettings I opened different ticket there. *** This bug has been marked as a duplicate of bug 1549096 ***