While online... drag everything over from one account to the other.
Apple Mail should just do that. That *should* in theory and most likely practice work just fine. If there is a lot of mail... it'll take a while.
I drag mail 'tween my gregfolkert.net and my gmail account all the time. Straight IMAP to Straight IMAP works better as Google has to "tag" the messages as they are put into an IMAP folder.
Works like a charm, as long as you are using IMAP.
Every 3-4 episodes they would finally attack each other and some stupid aerial melee would begin with missed attacks inevitably shattering backdrops while direct hits only propelled the enemy into backdrops for shattering.
289 ms