exchange inbound mail issue.

Do you have a firewall in between that is not allowing inbound port 25?  Have you tried downloading, installing and running smtpdiag from microsoft?  This tool is great at helping to find problems.

Try to see if you can telnet in to the public IP address to port 25  (telnet mail.nyah.com 25) from an external source. If you cannot make a connection it would indicate a router/fireall connectivity issue or the SMTPSVC may be stopped.

If you can make the connection, I would enable logging on the Default Virtual SMTP Server in Microsoft IIS Log file format and try to track some messages using Message Tracking.

Dan

"I can telnet to the mail server and seems ok"  It is not a firewall issue
I have had to change port 25 as the ISP blocks this.  Have changed and tested and can telnet.

Mail does just not seem to recieve.  Inbound.  Internal and outbound is ok.
Ill try again today incase of dns propogation delay and then will look into the message tracking.

Thanks

ok.  i can telnet to mail server on port 26 from external.  responds ok.
i still cannot get any mail inbound though.  and no bounce back.  its very strange.

im waiting for the logging to kick in.  is there anythign else i can look into in the meantime?

If you cannot receive email from external networks and there are no incoming messages at all I would definitely check your MX records and be sure they are correct.  Usually these are held at the same place hosting your external DNS if you do not host your own.  Generally this would be your ISP or another hosting service like GoDaddy or Register.com.  A good way to check would be to use the tools at DNSstuff.com and see if your MX records are showing up correctly or at all.  

changing port 25 to another port was the issue.
I contacted the ISP and got to unblock port 25.  change smtp port back to 25 and all ok.

Thanks for the follow-up...  Glad you got your issue resolved!