Server publishing and published server required to be secureNAT Client-a discussion

A discussion that explains this concept when you are using server publishing on the ISA server to publish services like smtp/pop3 etc

Please have a look

https://social.technet.microsoft.com/Forums/en-US/Forefrontedgegeneral/thread/16f7ff1a-e283-47f3-9597-9b1f4fb47c54