hydroxide Error 554; SMTP only works for proton recipients

Hello, I'm setting up IMAP and SMTP on a nextcloud instance. Sending smtp emails works, but only when sending to proton emails. If sending an email to another email provider, I see the email stuck in the draft box. Using MUTT to see more details, I get : "SMTP session failed: 554 5.0.0 Error: transaction failed: cannot send message: [2001] Message signature is missing or invalid" Using latest version (0.2.30) of Hydroxid on FreeBSD.

Nov 08 '25 01:11 clemtrinc

Hi, I managed to fix this issue by simply rolling back the hydroxide version to 0.2.28. No more errors when sending mail to non-Proton email addresses.

Nov 14 '25 11:11 oleksulkowski

I am experiencing this too on 0.2.30. Could this be prioritized? It's a big deal not to be able to send to other email addresses than proton's

Dec 04 '25 23:12 dehekkendekrekker

I can replicate this too

hydroxide-0.2.30_6 on FreeBSD:14:amd64 with thunderbird-146.0 . Sending to other proton mail accounts works.

Dec 11 '25 20:12 poksiala