Messages get stuck in outbox without any indication of the problem, no (obvious) way to cleanly resolve the block
Bug Summary
After writing a message, the message may get stuck in the Outbox. This happens to me every few weeks or so. There is no indication of the error/problem/issue in Geary. Once this happens, all new messages are also stuck in the outbox, again with no obvious indication. I typically only notice the problem once people become upset because they did not receive any answer from me. The only (awkward!) way to unblock the outbox seems to be to delete the oldest message from the outbox, as it cannot be moved from the outbox to drafts for further editing/inspection and re-sending (or at least I could not figure out any way to do that).
Your installation
Geary 44.1 (Debian/44.1-1) on Debian trixie/sid, installed from Debian repositories SMTP/IMAP email server