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?