Hi, From "Certificate Use in Exchange Server 2007" (http://technet.microsoft.com/en-us/library/bb851505.aspx), I got the impression that Outlook 2007 supports using wildcard names in the certificate. But every time when start Outlook after I upgraded to Outlook 2007 from 2003 on Windows XP SP2 (or Vista), I got a Internet Security Warning - The server you are connected to is using a security certificate that cannot be verified. The target principal name is incorrect. I am using a profile for IMAP over SSL, not for Exchange. The server has a valid wildcard certificate for mailserver*.domain.com and the server that I'm connecting to is mailserver123.domain.com. The certificate doesn't show any errors and everything works fine after I accept the dialog. As I mentioned, the same machine was installed with Outlook 2003 and had no problem then. Also I don't have any problems with the same server and settings when using Outlook Express 6.0 or Mozilla Thunderbird now - while Outlook 2007 giving me the warning. Any suggestions on how I can avoid the message showing every time? Is there any "secret" checkbox or registry key which I can turn off this warning on Outlook side? Please note the mail servers are not Microsoft Exchange, so please don't suggest making changes on server side based some KB articles. Thanks in advance Eric