Sometime Monday afternoon Thunderbird started having issues connecting to Office365 as well as Google. It would try to fetch or send a message and just sit there trying and never finish. Restarting the software did nothing but if I’d reboot the system it’d work for about 5 minutes then it’d hang up again.
This was on Fedora 17 as well as 20.
During the course of trying to troubleshoot this madding issue I found no logged error messages. I set my workstation connections to go out 3 different routers, thru 2 different tier 1 connections. I tried eliminating NAT by setting the workstation to a public address.I checked dns, routing, firewall/filtering. Nuked my Thunderbird config and re-added the accounts.. even checked my workstation at home, also Fedora 20, and it works just fine there. I frankly was running out of ideas….
Then finally I got to looking at netstat output and I see Thunderbird is trying to connect to imaps using an ipv6 address! I reboot and start Thunderbird and see it connecting to an ipv4 address and it’s working. After about 5 minutes it stops working and now netstat shows pending ipv6 imap connections and the connection count just grows until there’s a dozen that never connect….
So, I disabled ipv6 on the interface…
It’s been over 15 minutes now and netstat is showing ipv4 connections to Office365 addresses so I **think** I”m good now… guess we’ll see…
This has driven me totally crazy (yeah, I know…) since Monday when it started and I could find absolutely nothing searching Google so I’m posting in the hope I’ll save some other poor soul some trouble.