Kmail sends e-mail with 30 sec. delay

Hi all,
I habe used Kontact for several years now but since the latest install on a different OS (Fedora 37) I’m having a weird issue. When I create an e-mail (or answer one) and click Send, the mail transfers to the Outbox. It stays there for exact 30 seconds (I timed that), then I see a notification in the corner of my screen and the outbox is empty.
I have 2 accounts: one G-mail which is a POP-account, and one Microsoft365 account which uses EWS. Both accounts show this behavior.

What can cause this? It is not that it happend once, it does this every time I send a e-mail.
Any help is appreciated very much.

If you open Kontact/KMail settings and then find Accounts and there open Sending tab, there are some settings for default sending mode and enabling/disabling canceling sent mail. Maybe these settings have something to do with it.

Hero name is Undo Send. This feature saved my ass for many times.


@JLP and @emp74ark: Thank you so very much. It now works again as it used to work. No idea why this tickbox was marked.
Great help, thanks.