I got the warning when I try to connect to https://mail.domain.com/owa Here is the system setting. computer name : mail2 ad domain name : domain.com mail server address on internet: mail.domain.com I've tried the steps in the following http://technet.microsoft.com/en-us/library/aa995942.aspx The result is: run at server on IE7 https://mail2.domain.com/owa <- no error run at lan on IE7 https://mail2.domain.com/owa <- got certificate error said: The security certificate presented by this website was not issued by a trusted certificate authority. Security certificate problems may indicate an attempt to fool you or intercept any data you send to the server. access from internet using IE7 https://mail.domain.com/owa <- got same message as above Could someone tell me how can I fix this? I think I have to fix this to make pocket PC sync with exchange 2007 from the internet.

It sounds like you have your own CA. To get rid of this you will need to install the certificate chain on your workstations. You can simply bypass this by clicking continue or you can purchase an ssl certificate from verisign or some where cheaper.