[Dovecot] dovecot + ssl + outlook

i have installed dovecot on my debian server.....

i have configured with imap + ssl

all ok but i have one problem

when I lunch for example outlook or outlook express appears this error

Title of error page: Internet Secuiruty Warning The server you are connected to is using a security certificate that could not be verified The certificate's CN name does not match the passed value.

Do you want to continue using this server?

If I click to yes ....it works.

please help me

thanks

Chris