MeysamMTA-STS: forcing TLS on your inbound mail.
SMTP was designed without encryption.
STARTTLS added opportunistic encryption, but it's trivially downgraded by a MITM stripping the STARTTLS response.
MTA-STS fixes this.
combined with TLS-RPT , you get reports when senders fail to establish TLS.
without TLS-RPT, MTA-STS enforcement is blind... you won't know when legitimate mail is being rejected due to certificate issues.
