[as a precursor to this, since it is my first question, I assure you that I will check the correct answer and not leave your responses unnoticed and unappreciated (I'm active on StackOverflow and AskDifferent)]
I've searched about a bit and haven't found a good answer to this question, so I've decided to ask my first one on serverfault:
We are in the process of migrating our clients from a MediaTemple dv server to a rackspace Cloud Sites server, and I have a question regarding emails and DNS.
We plan to keep our old MediaTemple server running until our credit on the account runs out, and during that time I would like to have the old webmail accessible in case any clients did not heed my warning and backup their emails from the old server when we switch their Name Servers to the new rackspace ones.
If I set up a new A record that points oldmail.domain.com to the IP address of our old MediaTemple server, will clients be able to log in to their old webmail and access any important emails they may not have backed up?
I'm not 100% sure about simply pointing it to the IP address, which is what the MediaTemple server currently does, because it just seems like it would pull up the hosting for that IP and not necessarily the webmail interface.
Thanks for any information/assistance you can provide.