You can't enforce remote peer to use SSL unless that peer is under your control.
Maximum that you can do - enable STARTTLS and configure MTA-STS (rfc8461). чт, 15 авг. 2019 г., 9:53 Eliza <e...@chinabuckets.com>: > Hello, > > My MTA (postfix) has both 25 (non-SSL) and 465 (SSL) ports enabled. > > How to enforce the peer MTA send messages only to 465 port for better > secure communication? > > Can I just shutdown port 25? > > Thanks. > >