Wayne
What type of e-mail account is it? If it's pop3 then in Outlook make sure that in the account settings the e-mail address supplied there is correct. The e-mail supplied in that box could be anything, as long as it's valid, and this is the address the person will see and also reply to. If there is a spelling mistake in that then it won't be delivered
Hope that makes some sense. Let us know how you get on
Regards
Ash.