secure SMTP and cygnus-sasl handling

[admin]

Hi,

well I am a little new at the stunnel/secure SMTP options here so pardon the
simple question.  But I am reviewing all the documentation but cant seem to
figure out the answer here.  I am using cygnus-sasl as the method of SMTP
authentication.

I am using stunnel to map from port 465 to port 25 for SMTP authentication.
but I want to make it so users going directly to port 25 cannot authenticate.
 their only option is authenticate through port 465 via stunnel.

are there other applications that I need to consider here?

- Noah