Programmatically determining the maximum attachment size

I'm writing a VB.NET (VS 2005) application that exports files from a
document imaging system as Outlook attachments. I want to be able to
check each message's size against the maximum allowable attachment
size and prevent the application from even trying to add those files
(since they will fail anyway).

Now from doing some research I have found that this is not controlled
by Outlook, but rather by Exchange Server. Is there a way, via
Outlook Interop, to get the maximum allowable size from Exchange
Server? If not, does anybody know a way to talk to Exchange Server
directly and get this number?

If all else fails, I'll simply find out what the max is from my IT guy
and either make it a constant in the application, or store it in
My.Settings (so I can change it without a recompile if need be), but
I'd much rather pull it programmatically, so I wouldn't have to do
ANYTHING if this number is changed.

We're using Outlook 2007 and Exchange Server 2003 (with 2007 waiting
in the wings). Thanks for any help anybody can give!