Re: [CentOS] Forcing TLS for SMTP?

On Wed, 04 Dec 2019 15:14:32 -0800 Lists wrote:

s there a useful defense against STARTTLS being stripped from unencrypted communications?

To what end? Just for your own information? If so you can get it from your logs.

Or do you want to prevent communication from happening at all? In that case, you could still get it from your logs. IP address X strips the encryption, so now we'll blacklist it. You could probably automate that analysis and blacklisting.

Of course, then you won't be able to communicate with that guy any more, which might not be a great idea if you're trying to do business with him.