" ::1" is a local address for IPv6 "127.[something]" is a local address of IPv4. https://en.wikipedia.org/wiki/Localhost
My guess is that you didn't include IPv6 address to the list of "mynetworks", so Postfix can't "trust" it, because "smtpd_relay_restrictions" is default to: "permit_mynetworks, permit_sasl_authenticated, defer_unauth_destination", which means it only relays emails either from "mynetworks" or authenticated users. "localhost" is resolved to the IPv6 address on CentOS. You can explicitly disable IPv6: https://www.tecmint.com/disable-ipv6-in-centos-8/ Or use IPv4 address explicitly: "telnet 127.0.0.1 25". I'd stay with the latter case. On Mon, Oct 12, 2020 at 5:55 PM Jason Long <hack3r...@yahoo.com> wrote: > Thank you for your reply. > How can I sure I'm using IPv4 or IPv6? > > > On Monday, October 12, 2020, 06:18:10 PM GMT+3:30, IL Ka < > kazakevichi...@gmail.com> wrote: > > > mynetworks = 127.0.0.0/8, My Public IP > > Trying ::1... > It could be that you are using IPv6 to connect while "mynetworks" is IPv4 > address. > Try "telnet 127.0.0.1 25" >
