[stunnel-users] feature ? authorizing only given certificates ?

Hello My european organization is using a certificate chain which signs tens of thousands of user certificates. My local organization counts 300 users ...  and i only want these 300 to get in the IT system. I'd like to know if there is a way to restrict the connection to a subset of certificates ( for example based on a list of authorized emails which are written in the certificate )

Sincerely  Fred