In my company there is another person who shares my name but has a different
alias.  I frequently receive emails that are intended for him.  In this case
both the senders and the intended recipient are in England.

My suggestion is for Outlook to detect when the correct alias for a
recipient's name is ambiguous and to prompt the user with a dialog that says
something like "Always send emails for John Smith to josmith@abc.com?"  And
then never prompt me again when I need to send an email to John Smith, since
it now has a rule that will automatically maps John Smith to josmith@abc.com.