Exchange 2010 error 451 Open relay not allowed

Question

_{Sunday, October 3, 2010 1:03 PM}

Hi,

I have Exchange 2010 and 2007 in a co-existence. I moved a mailbox to the 2010 server. I cannot send mail to the 2007 server or externally. I can telnet on port 25 to our external mailfiltering service and to the Exchange 2007 server.

I can receive mail from internally and externally on the mailbox that is sitting on the 2010 server. Public folders are replicating.

I can see the emails sitting in the queue with "451 Open Relay Not Allowed"...

Forefront Protection 2010 with rollup 1 is also on the 2010 server

The 2010 server sees the send connectors that are on the 2007 server and I added in the 2010 server as a source server

All replies (2)

_{Sunday, October 3, 2010 1:36 PM ✅Answered | 1 vote}

Hello,

In E2010 Server à

Check permission on Default Receive connector and checked Anonymous users permission.

Create a proper SEND Connector on E2010 Server

** **

In E2K7 Server à

Check permission on Default Receive connector and checked Anonymous users permission.

Create a proper SEND Connector on E2k7 Server

Please check whether IP address of the E2010 is added on any of the Receive connector then Removed the IP.

Please check if you have any Receive connector on E2K7 other than client & Default Receive <SERVER> connector then please disable it for some time.[After checking the mail flow Enable it]

Restart the Microsoft Exchange Transport service  on both server.

Checked the mail flow between the server – It should work.

It Will fix the problem.

EXCHANGE2010, MCSE, MCTS, MCSA MESSAGING, CCNA & GNIIT

_{Sunday, October 3, 2010 2:49 PM}

Hi,

thanks for your reply. It turned out to be an issue with our External mail sweeper...all working now