Question : Do Not Have Permission To Send/Unable To Relay

Hi, I'm running Exchange 2003 on Windows 2003 (latest SPs for both).
Recently, my users and I have noticed a problem with replying to some emails.
We will get an NDR stating "You do not have permission to send to this
recipient. For assistance, contact your system administrator.
#5.7.1 smtp;550 5.71. Unable to relay for
[email protected]om>." This only happens on replies and only
sporadically. If the user resends, the message might go through or if the
user creates a new message, the message will go through. There is no rhyme or
reason as to which domains it happens to or what users. I don't have relaying
turned on. I only have one domain name setup on my Exchange server; no
connectors either. Also, all of my users use Outlook as Exchange clients.
Any help is greatly appreciated.
Thanks.

Answer : Do Not Have Permission To Send/Unable To Relay

The error does not mean the problem is with your server. It could be a remote server rejecting the message at the point of delivery. All it means is that the NDR was generated on your server.
Therefore you have to look at the SMTP logs and Message Tracking to see whether an external connection attempt was made at the time. That will tell you where the problem was.
Of course if there is an external connection then the problem is outside of your control.

-M