Emails not visible until action taken

[Guest]

I have a user with Outlook 2000 on and XP machine which is exhibiting strange
behavior:
Whenever someone sends him an email, it does not become visible in his inbox
until he performs some other action in Outlook! However, hitting send/receive
does NOT cause the email to become visible. But hitting reply, or scrolling
down the email list, virtually any other action in the Outlook window will
cause the email to become visible. I'm baffled. Anybody got any clues?

 

[Vanguardx]

I have a user with Outlook 2000 on and XP machine which is exhibiting
strange behavior:
Whenever someone sends him an email, it does not become visible in
his inbox until he performs some other action in Outlook! However,
hitting send/receive does NOT cause the email to become visible. But
hitting reply, or scrolling down the email list, virtually any other
action in the Outlook window will cause the email to become visible.
I'm baffled. Anybody got any clues?

http://www.google.com/search?q=+Outlook++Exchange++UDP++notification++poll

http://support.microsoft.com/search...xchange+udp+notification+poll&KeywordType=ALL

Short and skinny: There is something blocking the UDP notification
packets being sent to the problematic host running Outlook.