Mail Servers - Dual Delivery?

[William Attwood]

Hello--
   I'm hosted at 1and1.com and am switching over to Google Applications,
primarily for their mail server.  However, at $50.00 a pop per mail account,
I'd rather have some e-mails delivered to one mail server, and others, to
another - to facilitate a few cronjobs that access e-mail accounts.

   How can I accomplish this? Do I need a primary mail server that directs
depending on what the e-mail address is?

Thanks,
-William