I had some problems with deliverability to gmail and G-Suite email addresses for a while. It turned out that disabling IPv6 for sending to Google's mailservers fixed this problem (which is weird, because the address wasn't blacklisted and a PTR record was set up). Usually, I would not tell you to disable IPv6. But with this trick, you will only disable it for mail to google, not for others. Open the master.cf: Code: nano /etc/postfix/master.cf Add this at the end: Code: smtp-ipv4 unix - - - - - smtp -o inet_protocols=ipv4 Now open the main.cf: Code: nano /etc/postfix/main.cf Add Code: hash:/etc/postfix/transport to the setting Code: transport_maps = The line looks like this for me: Code: transport_maps = hash:/etc/postfix/transport, hash:/var/lib/mailman/data/transport-mailman, proxy:mysql:/etc/postfix/mysql-virtual_transports.cf Now open the transport file: Code: nano /etc/postfix/transport And add this: Code: gmail.com smtp-ipv4: google.com smtp-ipv4: *.google.com smtp-ipv4: googlemail.com smtp-ipv4: *.googlemail.com smtp-ipv4: Run the following commands to apply the changes: Code: postmap /etc/postfix/transport systemctl restart postfix
