A message sent from one mailbox shows up a "sent" in a different mailbox.
Using Gmail on Thunderbird. I have 4 email boxes. Copy of mail sent from one box is showing up as "sent" in a different box. I have checked the setting in "copies and folders." All other boxes are behaving themselves.
Alla svar (1)
Do the Sent messages on the errant account show the expected "from:" address?
I think it's possible this account is using another account's smtp server.