I’m a brand new user to /e/os and murena. I have a Fairphone 6 only a few days old. I can receive email to my murena.io account fine, but sent mail is stuck in the outbox. I’ve tried test mails to various accounts. I have checked the outgoing mail settings against the guide on this forum and all seems OK.
Please see whether, navigate to Inbox > Swipe down from top of screen > does this cause a visible “waiting spinner” for a few seconds, does Outbox then clear?
Had the same problem and could not solve it. Emails to known contacts have been send but not to unknown contacts. Now I’m using Fairmail as an alternative, without issues but I have no idea what went wrong. But this could be the solution to compare and align the settings and test them on both Mail Apps.