I can OWA into any account just fine from remote locations.  I have recreated send and receive connectors a couple different times.  I can telnet into the server while offsite using the FQDN and port 25.  When on the Exchange server itself I cannot telnet to it, though I'm not sure if that is normal or not.  The old server is still up and running and was sending and receiving email just fun until I changed my port forward in my router to point to the new server to test mail flow.  All but one of the email accounts are still on the old server but I did move one account to the new server for testing.  I can OWA into that account without issue.  If i go into my queue on the server i have approximately 30 email in there and and error message.  451 4.4.0 Primary target IP address responded with: "421 4.2.1 Unable to connect." The mailflow troublshooter comes back with "5.3.3 unrecognized command" which from research I see can be due to lack of space on the hard drive, that is not the case on this server.

Aside from that I have tried too much to list.  Suggestions would be appreciated.

*Old server is Server 2008 SBS
*New Server is Server 2012 with Exchange 2010 SP2

Are you sure about these versions:

"New Server is Server 2012 with Exchange 2010 SP2"

As that is an unsupported combination. You should be on Exchange 2010 SP3 with the latest rollup to be supported.

You should be able to telnet to port 25 on the server. If you cannot then either something is blocking it or you have restrictions on the Default Receive Connector. Ensure that you have anonymous enabled on the Default Receive Connector as well.

However if you really are on SP2, then you need to upgrade first before you do anything else.

Simon.

Agreed - please ensure you're on a supported version of Exchange 2010. See here: https://technet.microsoft.com/library/ff728623(v=exchg.150).aspx

Looks like you have issues sending email out also.

If you're using a smarthost, ensure that you can telnet onto port 25 of the smarthost. You need to ensure your server has outbound access to the smarthost on port 25 on your firewall.

If not using a smarthost, ensure you can telnet onto port 25 of mx1.hotmail.com (just a randomly picked MX record). You need to ensure that your server has outbound access to the internet on port 25 on your firewall.

Thanks.

Hi,

The possible causes for the 451 4.4.0 Primary target ip address responded with: "421 4.2.1 Unable to connect." are:
1. Your hub transport server or edge server are unable to resolve the external domain names. It can be caused by the incorrect DNS sever settings.
2. Your firewall or ISP block the outbound traffics on port 25.
3. The IP address of your hub transport server or edge server are blocked by the target domain or other issues on the target domain.
4. The Simple Mail Transfer Protocol service is not running and set to start manually.

Also, use Telnet to test SMTP communication:
https://technet.microsoft.com/en-us/library/bb123686(v=exchg.141).aspx