So I have a really wierd issue. Any help would be greatly appreciated.
Internally we have a 2010/2013 org with:
Exchange 2010 - 2x CAS&HT , 2xMBX, 2xEdge Exchange 2013 - 2x CAS, 2xMBX
I am trying to subscribe my Edge Transport servers, that also run TMG firewall, to the Exchange org after installing Exchange 2013, so that I can send email out through Exchange 2013. However, I cannot telnet on port 25 from one of my 2013 Mailbox Servers to the Edge Transport. This works:
2013MX1 to EDGETMG02 2013MX2 to EDGETMG01 2013MX2 to EDGETMG02
However, if I telnet on port 25 from 2013MX1 to EDGETMG01 then I get an error 421 4.3.2 Service Not Available. What does this mean, and what can I do to fix this? At the moment email just queues up on Exchange 2013 without any route out to the internet.
Edit:
Exchange 2013 servers are all SP1 CU6 Exchange 2010 servers are all SP3 RU4