I have an exchange 2007 environment with about 30 domains in it. We bought a Unified Communications Certifiate for our main domain, call it domain1.com This had the following names in it: mail.domain1.com autodiscover.domain1.com server5.domain1.local This stopped the certificate error popping up when we opened outlook, at least for the people who have a domain1.com email address. Unfortunately for users of the other 29 domains they get a certificate error on launching outlook and other things such as using "out of office". The error says "autodiscover.domain2.com - The cert is trusted, The cert date is valid, The name on the cert does not match" I cannot put all domains in the cert and I cannot buy 30 certs, so how else can I resolve this problem? I found this: http://bit.ly/eWdpok but I don't quite understand it so if anyone could better explain I would be very greatful. Thanks, Leigh