Hi! I’ve recently installed Thunderbird, and just now I’ve noticed that I’m unable to send e-mails. After a while, they time out: [Screenshot_20251208_140837] After reading this post, I disabled IPv6 and, at first, thought that I’d fixed the issue. However, e-mails still time out, and I can only…

Yeah, it seems to be this one: 1993576 - Sending messages with an O365 account is unworkably slow and times out "The message could not be sent because the connection to (SMTP) server smtp.office365.com timed out" Symptoms match, including the point during the conversation where the timeout happens.…

just quick check, have you added the firewall settings for it (ufw is turned on by default in desktop version) ? there should be IMAP and IMAPS profile in ufw

That’s not correct, these ufw settings are for incoming connections, not outgoing

Okay, thanks for the info! According to the settings, the default for outgoing connections is already allow. I still went ahead and added explicit rules for outgoing connections on IMAP and IMAPS. It’s still strange that I can sometimes send e-mails, and sometimes I can’t. It seems to change from se…

Just guessing at it having something to do with the systemd-resolved default resolver? Maybe see these other threads; [image] CachyOS Hello DNS Settings Disable Issues & Assistance I dont think there are the kinds of buttons you are looking for there. But if…

Hmm, yeah, a DNS issue seems likely. If the default resolver is caching the IP too long, the server might become unreachable without apparent cause. I’ve gone ahead and set [Resolve] DNS=1.1.1.1 FallbackDNS=8.8.8.8 Domains=~. DNSStubListener=no Cache=no in /etc/systemd/resolved.conf.d/zz-nostub.co…

Don’t disable cache or the stub resolver.

[image] Dante_05: EDIT: Okay, first thing I’m noticing: Neither drill nor dog will resolve any domains anymore. I can ping and access websites normally though. Anything I can do to resolve this? Thats unexpected. After a reboot as well?

Yep, I reactivated the stub resolver and cache, and it works again. I haven’t had enough time to do any thorough testing with Thunderbird. I’ll turn it back off and get back to you. EDIT: Forgot to mention: The error dog spits out is Error [network]: Connection refused (os error 111)

Update: No dice on the stub resolver fix. I’m still getting timeouts. (tagging @cscs - any other ideas would be appreciated :slight_smile: )

Depends which server refuses the connection. Could you add an extended log? Is it maybe a sketchy server, which might be unstable? Oh, its Microsoft, so it should still be stable.

Thunderbird - can't send e-mails

Issues & Assistance

cscs December 14, 2025, 9:39pm 5

Just guessing at it having something to do with the systemd-resolved default resolver?

Maybe see these other threads;