Connection to Host Lost

I have a Server 2003 R2 (fresh install) Exchange 2003 Enterprise and ISA 2004. However I cannot connect to the SMTP server from an external connection. If I telnet localhost 25 no problem but if I telnet the external ip address from another external address the server connects and then immediately drops the connection with connection to host lost.
I'm sure it is something to do with the ISA server but I don't know what.
Any suggestions welcome.
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Matthew MillersCommented:
Is there an option where you can tell the connection to appear as though it is from the ISA server? Enable this.
jonesc3MDAuthor Commented:
Sorry. That makes no difference. All the ISA Rules are in place and appear correct. i.e I have checked them against another server I built some weeks ago which is working fine.
The only difference I have between the two servers is that one is running Exhange 2003 Std and the other is Enterprise.
jonesc3MDAuthor Commented:
Sorry.. An upddate.. ISA 2006 not 2004.
removed ISA server 2006 and everything works again
so trying another install of ISA 2006
jonesc3MDAuthor Commented:
Solved it!
Noticed that RDP was working when it was defined as an access rule, so once the rules were defined manually using the Create Access rule, instead of the publish mail servers it worked fine. we have a virtually identical server which on which the publish mail servers option worked perfectly fine

Hope this helps anyone with a similar issue

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