wrote:

Then with another group of 10 I hit 'SEND' and is says an address is
immediately rejected. It may or may not tell me which is bad. The
message is removed from the Outbox. Did I send the other 9?

Generally, yes.

What is wrong with the address?

Usually displayed in the rejection notice.

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.
--
Brian Tillman