One of my clients seems to have a glitch in his Outlook 2003 email, with the
way email addresses appear in the Select Names list when you click the ‘To’
button in an email.  

It seems that some entries are not showing their email addresses in the
Select Names box, even though they have an email address when you look at
their Contact card.  The one thing all these misbehaving ones have in common
is that in the Contact view, the ‘Display as’ box shows them with their name
followed by their email address in brackets.  This seems to be the way
Microsoft defaults, and you have to actually change that display manually if
you don’t want it that way.

I’ve tried it with my Outlook and I don’t have the same problem.