Retract dialog can duplicate cancellation mails
This had been reported on the mailing list:
https://lists.osuosl.org/pipermail/evolution-users/2024-February/167305.html
It looks like deleting a meeting on an EWS server sends multiple mails to each recipient, not only a single message. One can be from the retract response (cancellation mail with comment). Verify the reason and figure out what can be done with this.
The CalDAV calendars which handle meeting invitations can be also affected.