ssl over pop and imap in dovecot in rhel 5.3

i had configures senmail and dovecote in rhel 5.3, as it was working fine with pop3 and imap, but it will not work for pop3s and imaps .the cerificate is chkd with mutt it is fine , on client side i use outlook express/Thunderbird . the ports status shown as listening . moreover the certificate was not trusted by the clients. is there any more setting i have to do . i had configures senmail and dovecote in rhel 5