Question : Exchange problems -- Email not getting to some recipients

New Exchange server 2007 setup.  I keep on getting the below message when going to a few email addresses.  I can send most stuff out.  When those users try to send things to me they are also unable to send things to us.  What can I check

Delivery is delayed to these recipients or distribution lists:

[email protected]

[email protected]

Subject: test

This message has not yet been delivered. Microsoft Exchange will continue to try delivering the message on your behalf.

Delivery of this message will be attempted until 3/8/2008 2:16:07 AM (GMT-06:00) Central Time (US & Canada). Microsoft Exchange will notify you if the message can't be delivered by that time.

Answer : Exchange problems -- Email not getting to some recipients

looks like a connectivity issue

can you reach the MX machines for those domains? if not, then exchange will continue to try send until it times out and generates an ndr