I've never tried it, but perhaps she can use the "
Message->Copy to" command? There is probably already an "
Archive" mailbox in all your accounts. You can also create a new mailbox just for "SWIMBO Messages". I just tried the "Copy to" on a message and then deleted it,
Quit and
Restarted Mail and the test message was still where I copied it. That location
is a separate account from where is was originally, however.
I gave up my attempt to get my wife to 'trim' her old (EarthLink/Mindspring) email account. I just paid for a couple of GB of storage...