Sent mail showing up in Inbox
Since upgrading my iMac to Sonoma last week, I have been getting Sent emails popping up in my Inbox at random. It seems to always be 3 days after I sent them. Variable numbers - the first time it was 5 or 6, lately it's been just one a day. No pattern of addressee, topic or email address sent from. These emails are no longer in my Sent folder if they show up in my Inbox. I have tried to use Move To to move them back and they do go there, but they will always come back into the Inbox.
How can I get this to stop?