Hello All, i want to remove the security message when access OWA because of the exchange self signed certificate, so my question if i purchased a certificate from Godaddy or Network solution should this work or i must install thier CA certificate on my client computers??

The whole point of purchasing a certificate is so that you don't have to install anything on the client machines. Therefore if you use someone like GoDaddy then there will be no certificate prompts. There is no difference between the GoDaddy and Network Solutions/Verisign certificates, other than the cost. The GoDaddy certificates take another 30 seconds or so to install (there is an extra step) but that is exclusively server side. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Agree, + You don't have to install the certificates on Client computers. Gulab | MCTS-MCITP Messaging: 2010 | MCTS-MCITP Messaging: 2007 | MCC 2011 | Skype: Gulab.Mallah

Thanks for the answers but what if the publisher is not listed in the Trusted Root Certification Authorities ? will the server install the CA certificate as well as the certificate used by the exchange server ?

Many of the certificate providers will issue a root and/or intermediate certificate to install on the server, That is all that is required. It is not unusual for servers to have fewer root certificates than the clients. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.