Whyvon wrote:

Thank you! What do you mean "resolves an address"?

When Outlook uses the Address Book service to obtain the mail address of a
recipient from your Contacts folder, it's called "resolving" the entry.
Outlook signals to you that the entry is resolved (i.e., an address was
found) by underlining the entry in the recipent field.

Also - what determines then - how the recipients name appears in the
"TO" field when they receive the message?

A combination of what you include and what the recipient's client wishes to
show.

Let's keep this to a single thread from this point on, shall we?
--
Brian Tillman