Sent mail sometimes appearing in Inbox

I have a user who sometimes gets a copy of an email he has sent appearing in his Inbox. It also appears in the Sent view (as you’d expect). He isn’t using Send & File on these occasions, and it only happens now and again (about twice a day). The email has the envelope icon next to it.

Can’t figure out what’s going on here - any ideas?

Thanks,

Neil Parry

Subject: Sent mail sometimes appearing in Inbox

normally that only happens if the message is saved as well, but the users not doing that. any chance it was previously saved as a draft and somehow thats causing the issue?