Can’t receive email

Hi folks,

I got this problem with an employee(let’s say user A) that can’t receive email from another employee(user B). I use Exchange 2000 and Outlook 2000. The person can receive emails from any other user inside the organization but this one specific user(user B). Even if user B sends an email to an entire group, everybody else receives the email but user A

Any suggestions on where to start looking for the issue?

Any help would be appreciated.