External connection to Postfix problem

[Gary Brinker]

Hello, I'm new to this group but was prompted to try your thoughts on the following message I posted to the Postfix user group, where they suggested it was not a postfix issue and I should try here. I'm not a Linux expert but believe I have all firewall filters off. Thanks for any suggestions.
Gary
 
Because of a hardware failure on an old installation of a postfix gateway I 
took the opportunity to install an up to date version on an Ubuntu server. I am 
not too far into the configuration but am having a basic problem with accessing 
it from external sites. I think I can eliminate the usual DNS and router 
configurations as it did work correctly with the old system. 
The issue is 
that I can telnet into it internally with no problem but cannot reach it 
externally. I hooked up wireshark and if I'm interpreting it correctly I do find 
the initial SYN come in but no connection is established. My reading suggests 
that I may have an ownership or permissions problem, but I'm not finding success 
in isolating the issue.
Can anyone point out specifically what I should be 
looking at to diagnose and correct this so I can get on to the meat of the 
configuration.

 		 	   		  
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