This patch is floating in the bug system on SourceForge. Upstream
develoment is slow/nonexistent.
If you have IPv6 mail servers and run sqlgrey you may notice emails from
places like GMail sometimes get lost or take forever to get be received.
This is because GMail does not retry from the same server, and they have
a large pool of IPv6 capable MTAs. For IPv4 sqlgrey handles this by
whitelisting the entire /24, but similar logic for whitelisting a /64 in
sqlgrey doesn't work consistently. This fixes it.
PR: ports/182440
Approved by: crees (mentor), maintainer timeout
e9316e97ba