Technical Tip: How to configure IPv6 preference for outgoing connections.
| Description | This article describes how to prioritize IPv6 for outgoing emails. |
| Scope | All FortiMail versions. |
| Solution | To use IPv6 addresses when relaying outgoing emails.
When FortiMail delivers email to a host name, it does DNS AAAA and A record lookup.
Use the commands below to:
- ipv6: try IPv6 only. This setting is not recommended.
- ipv6-ipv4: try IPv6 first, then IPv4.
However, if the AAAA record does not exist, the extra AAAA DNS lookup for IPv6 addresses will potentially cause email delivery delay.
# config system mailserver set smtp-delivery-addr-pref {ipv6-ipv4 | ipv6} end |
