How To Fix Email Service Unavailable Delivery Issues with IPv6 on Amazon Linux
erics, July 16th, 2021
PROBLEM: Email delivery to Google was failing with a “Service Unavailable” error:
1 |
relay=aspmx.l.google.com. [IPv6:2607:f8b0:400d:c0c::1a], dsn=5.0.0, stat=Service unavailable |
Note that the network address for the destination is shown as IPv6! That is the root cause of the issue: 1. Sendmail is sending mail from the IPv6 address instead of the IPv4 address 2. Google rejects IPv6 senders without proper reverse […]