If the name is not in format, then it performs a lookup on the user's address lists, according to the address resolution order set in Tools | Address Book, Tools | Options. If the user has the wrong address, Outlook doesn't know or care.

--
Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
http://www.turtleflock.com/olconfig/index.htm
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers
http://www.outlookcode.com/jumpstart.aspx

"Brian Tillman" wrote in message ...

What does the 'Tools' . 'Check names' do? Does it just check against
the address book or does it check the validity of the addresses
against internet URLs?

It's resolves the name, but I'm not sure of what all that entails. Russ may
be able to say.