exchange 2003 inbound email

Perhaps port 25 is being blocked at the firewall.

Sorry, I should have been more explicit before posting the comment about the firewall. I had already checked the MX record and then tried telnet to that IP address. It failed to get a response so that suggests the firewall is either blocking port 25 or not forwarding it to the right server. There might be other problems as detailed above, but you need to check the firewall first.

follow the following article to test smtp using telnet, you should try to connect it from any system with in your local lan if it succeeds then you should check that your smtp is listening on both ip's if it is directly connected to the internet or check your firewall configuration, router etc. but first check it from local network to be sure smtp is working on standard port 25. (use internal ip instead of external to check it locally then use external to check both sides)

http://www.amset.info/exchange/telnet-test.asp

One other thing to check is antivirus applications, macaffe virus scan 8 blocks port 25 by default.

Everything passes on the DNS report.
http://www.dnsreport.com/tools/dnsreport.ch?domain=puroflux.com

The only thing it fails on is what your server is announcing itself as.

Therefore considering the age of the question, I am wondering if you had only recently made the DNS changes and not allowed them to propagate round - which takes 48 hours.

Simon.