Make sure you aren't delivering over IPv6. I had all my IPv4 rules set up, and mail worked fine - except delivering to gmail. Turns out I was delivering over IP

Make sure you aren't delivering over IPv6. I had all my IPv4 rules set up, and mail worked fine - except delivering to gmail. Turns out I was delivering over IPv6. I wound up shutting off my IPv6 interface. As a good netzien I should work to behave on IPv6, but it was just too much of a pita for my tiny, single user server which works fine on IPv4