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Cannot send e-mails externally from Exchange 2010

My organisation had one Exchange 2003 server, and we have recently purchased two new servers, and I have installed Exchange 2010 on both.  I have also set up a DAG to cluster the Exchange 2010 databases, using a fourth server as the witness server.

Mailboxes on the Exchange 2003 server can successfully send and receive both internal e-mails and external e-mails.  The test mailbox I have setup on one of the Exchange 2010 servers can successfully send and receive internal e-mails, and can receive e-mails from external sources, but cannot reliably send e-mails externally.  Yesterday some messages I sent at approximately 3pm were finally delivered at 7pm.

Interestingly,  I can Telnet to port 25 of MX servers from my client PC, and other servers, but when I try and Telnet to the same MX servers from either Exchange 2010 server, I am unable to do so, and get the message “Could not open connection to the host on port 25: connection failed”.

There are three Send Connectors on the Exchange 2010 servers, one which was created automatically on installation and relates to the Exchange 2003 server, and two I created, one for each of the two Exchange Servers.

There is only one Routing Group Connector in the organisation and this was created automatically on the Exchange 2003 server when I installed the first Exchange 2010 server.

I have setup our firewall to allow outgoing SMTP traffic from the new 2010 servers, and have tried disabling the anti-virus software on both servers to rule that out.

I am using two network connections on each 2010 server, one with a 10.10.0.0 address as per the rest of our internal network, and the other with a 192.168.0.0 address for replication between the two servers, and they are linked using a cross-over cable.

Can anyone help?
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vphul
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vphul
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1 Solution
 
serchlopCommented:
You have to create a new send connector in your exchange 2010 to internet. Select hub transport  in enterprise config. In exchange management console - send connector - new send connector - in wizard select internet for the conector.
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vphulAuthor Commented:
I've done that already on each 2010 server.
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ckeshavCommented:
You might have configured Exchange 2003 to send mails to external host through a smart host. There you would have allowed only the Exchange 2003 IP.

Also add the Exchange 2010 IP's in the list and give a try
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vphulAuthor Commented:
We don't use a smart host.
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ckeshavCommented:
How is external mail delivery happening from Exchange 2003
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vphulAuthor Commented:
Through an Internet Mail SMTP connector.
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vphulAuthor Commented:
The queue viewer is showing the following error message.

451 4.4.0 Primary Target IP address responded 421 4.2.1 unable to connect.   Attempted failover to alternate host, but that did not succeed.  Either there are no aternate hosts or delivery failed to all alternate hosts.
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serchlopCommented:
Maybe the problem is related to comunicate from server 2007 to internet. try using tracert destinationserver.com and verify internet connectivity and try connecting with telnet to destinationserver.com in port 25. Sometimes ISP block use of 25 port.
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vphulAuthor Commented:
Hello Serchlop,

I can successfully use tracert from the Exchange 2010 servers to the destination mail server, but I can't connect to any mail server using Telnet and port 25.
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vphulAuthor Commented:
The problem has now been fixed.  It was a firewall issue.  Thanks to everyone for their contributions.
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ckeshavCommented:
ok
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vphulAuthor Commented:
I discovered the resolution to the problem.
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