John Allen:
> > What level of encryption are you contextualizing? STARTTLS between
> > SMTP peers; or the message itself using S/MIME or PGP/GPG; or
> > something else?
> >
> The message itself (S/MIME or PGP/GPG).
> Its a medical practice. They have sending under control, but they are
> concerned that they may be liable for breaches in patient privacy if
> they accept un-encrypted emails.
I think that this requires an smtpd_proxy_filter. Postfix header/body
checks can trigger only on the presence of text, not its absence
(the reason is that these mechanisms do not remember the result
from previously-matched text).
Technically, these filters can only detect plaintext when it is
already too late (i.e. they cannot predict the future when the remote
SMTP client sends the DATA command).
Wietse
