I keep a separate IMAP account to store my email archives, and on my primary account I have set the Archives setting to `"Archives" Folder on: the other account`. But for some reason, in certain cases the Archive operation moves the selected email(s) to the Archives folder on my main account. I couldn't really figure out what it depends on. Initially it appeared that maybe whether the UI focus is on the message list pane or the preview? But I tried selecting two emails in the message list pane and archiving them, which moved them to the correct account/folder. But when I moved those back to the main inbox, and selected them together with a specific third email, then all three got moved within the main account. This gets really annoying.