I am writing an application that must send encrypted email to recipients. The state agency I work for recently installed a feature for outgoing email. If #secure# appears anywhere in the subject, the email will be sent via TLS.
I spent the morning reading about this. What I found says TLS applies between servers, but not between client and server. For instance if I send an email and it is flagged as TLS, my SMTP server will not send the email to the destination server unless that server accepts a TLS connection. That's good. But what about the client who connects to the destination server to download email or read online?
I do not read any enforcement exists for that. Unless I can find such exists I cannot take advantage of the email feature my state agency has installed and I will need to encrypt using zip file attachments. Is there any such enforcement?