I'll confess this is an area where I'll give it 10-20mb and toss out an "email is not intended for file transfer" whenever a user gripes about having to use FTP.
But a shiny new mail server deserves a rational approach... so what is a non-voodoo method for determining an appropriate limit for attachment size?
(Wavering on whether this is a wiki, or if there's a method that's Just That Good.)
I thought there would be some good guidelines independent of environment, but specifics were called for - so 50 mailboxes, exchange 2007, AD, hardware is TBD. Clients are a 2007/2003 mix, I figured I'd set sent/received to match, just to keep things simple.