''colinjohnston [[#question-1073157|said]]'' <blockquote> I'm having the same issue as outlined here: https://support.mozilla.org/en-US/questions/1068987 Starting today I have been getting ''connection to server username@domainname.com timed out' errors. I was running v31.x so I updated to 38.x but I;m till getting the issue. - Two separate IMAP email accounts are failing; both are MediaTemple email accounts; neither config has changed; I'm able to access recent messages via iPhone and through webmail interface. - I've restarted Thunderbird in Safe mode, but that didn't help. I've checked password, and all other standard 'is it plugged in?' kind of things - I've gone into the config editor and upped the timeouts of mailnews.tcptimeout, mail.server.server1.timeout, etc. all to 300, no help here either Any ideas how to fix? </blockquote> Update: [Solved] Although everything else about my internet connection was working perfectly fine, I suspected perhaps this issue was related to other weirdness I experience with my Comcast DOCSIS modem. I rebooted modem and no more timeouts in Thunderbird. Again, I had no other apparent issues with connectivity, but my IMAP authentication uses port 993 and there must have been something wedged about that via my connection. Perhaps this info will help some folks troubleshoot they're way out of this issue.