Quoting Mark Rousell (mark.rousell@???):

> Option 1 is a bit embarrassing if anyone notices (e.g.
> "host-46462.static.bugtown.myisp.net" isn't too cool as the name of your
> mail server) but I don't see any technical downside, although DMARC
> might perhaps be an issue nowadays.

DMARC can be made to be a non-issue. ;->

:r! dig -t txt _dmarc.linuxmafia.com +short
"DMARC: tragically misdesigned since 2012. Check our SPF RR, instead."

I've had no problems _without_ DMARC/DKIM (but with a strongly asserted
SPF record). Have been operating home *ix SMTP smarthosts on static IP
with matching rDNS, and maintaining a clean, high-reputation system
since the 1980s.

I've tried to always have rDNS always match exactly my main mail server's
primary identity, though it has several valid alternate public identities
(uncle-enzo.linuxmafia.com, hugin.imat.com, unixmercenary.net) that in
my experience _also_ enjoy high reputation, despite A-to-PTR mismatch.

Basically, in my experience, some operators may be assigning a _very small_
spamicity score to 'rDNS exists but doesn't match': I cannot really
tell. What's clear is that 'IP lacks rDNS' is (rightfully) penalised,
given RFC mandate for same and its usefulness as an antispam heuristic.

And, of course, 'IP is part of a dynamic netblock' is very definitely an
antispam heuristic (though operating a public-facing SMTP host on
Dynamic DNS is RFC-compliant), so Don't Do That, Then.