Hello everyone. I just a beginner for ISA and MS product, I try to setup in test environment with exchange 5.5 and ISA 2000 on W2K as following: Router -------------ISA Server----------+-----Lan (10.0.0.xxx) xxx.xx5.6.225 xxx.xx5.6.251 (Ext.) | 10.0.0.1 (Int.) | | Exchange Serv. (10.0.0.250) After setup clients can browse outside web and can send mail ,but cann't receive mail from the outside, I try to check from the outside with Email-Validation from www.network-tools.com the result is fail the error message say about the email address has been rejected by ISA I have no idea about DNS setting up that I think that is a problem in this case. I will apreciate if anyone give me the idea or the example of DNS setup for local and where I should put DNS (I used ISP's DNS at External IP in ISA server). Best Regards, and thank you inadvance. Nathapol T. PS. - My Exchange Server is a DC. - My ISA is not a member in domain and no Active directory