Primary SMTP address of the account

Version: 2008
Operating System: Mac OS X 10.5 (Leopard)
Processor: Intel
Email Client: Exchange


As a user can have multiple SMTP addresses set, how do i get the primary SMTP address of the account from Entourage 2008.

The current user settings might be different than the primary SMTP account.

Any message property provides the primary SMTP address or do i need do a LDAP query to find it?

I need to talk to Exchange server 2007 using the primary address. Any other address used gives an error to use the Primary SMTP address

Thanks in advance