I have several email accounts set up in Mail, 2 of them imap. I have a lot of email folders "On My Mac." Today I happened to have the Activity window open and noticed that every time I perform an action involving a message that is in a folder On My Mac, Mail contacts the server for imap account A and performs some kind of transaction involving one of the folders there.

I noticed it when I flagged/unflagged a message, but it seems to happen when I do anything that changes something about a message. eg, flagging, deleting, moving to a new folder.

The puzzle is that the message I'm flagging/unflagging has no connection with the imap account -- it's not from that account and it is in a folder that has nothing to do with that account.

The imap folder involved is the top folder in the list of user-created folders there, so maybe Activity is merely showing that folder name as a default while it does something with the imap account in general.

I'm concerned that info about all of my mail is being sent to this imap server. Mail is only doing this with imap account A (the account with my employer). It's not happening with the other imap account -- a me.com account.

Any ideas why Mail is doing this?