Robert, how will you pick up the mail- by individual machine POP? If so, is the stream encrypted- because otherwise all your company e-mail, including confidential internal memos, will be transmitted in the clear across the internet.
We have e-mail servers in several countries but we've set up MX so they're only used if our main box (using Sendmail on Linux) goes down. When the in-house box is restored, it uses fetchmail to collect any mail that has accumulated in the ISP in the interim.
"... They ne'er cared for us
yet: suffer us to famish, and their store-houses
crammed with grain; make edicts for usury, to
support usurers; repeal daily any wholesome act
established against the rich, and provide more
piercing statutes daily, to chain up and restrain
the poor. If the wars eat us not up, they will; and
there's all the love they bear us."
-- Shakespeare: Coriolanus, Act 1, scene 1