🚀 go-pugleaf

me:
   > If you use sendmail, in S3 do:
   > R$*.$*!$*		$3@$1.$2		invert to @-format
   > but only after verifying that there are no @'s in the address already.
   > (That is, my use of the above rule is as the last stage of my Domain
   > Absolutist Rabid Rerouter ruleset trio.)

david@quad1.quad.com writes:
   I suppose. I thought that S3 wasn't quite the place to put it; In fact,
   I was afraid to put it into S1 as well, since that would affect mail
   "just passing through" my site.

I consider S3 to be the right place to do it because S3 is called
first for the purpose of canonicalization into the most correct form.
Or so I view it, anyway.  And yes, it affects mail "just passing
through."  I consider this a feature, not a bug.

   Furthermore, I suspect that the above
   rule matches more addresses than I would care to see attacked anyway -
   Wouldn't this turn "some.place!some.other.place!user" into
   "user@some.place.some!other.place"?  Or do I misunderstand the pattern
   matching rules?

The rule does the right thing, given that it's the last of the
previously mentioned 3.  The complete set is:

R$*.$*!$*@$*		$1.$2!$3		lose @-portion
R$*!$*.$*!$*		$2.$3!$4		strip excess left-hand
R$*.$*!$*		$3@$1.$2		invert to @-format

Note that the 2nd one is responsible for getting rid of all the
left-hand dotted-domain specifications except the last one.  Then the
3rd one turns it around.  (I suppose I should have posted the whole
set in the previous article, to avoid this confusion.  Ohwell.)

Before anyone flames that I'm violating numerous standards in the 1st
rule by deleting the RHS even if it's not "me," please first show me
_existing_, _real_world_ failure cases where this heuristic doesn't
work.  Yes, it's formally a violation of the RFCs; no, it doesn't hurt
anything on a practical basis, and since the practical basis is the
goal (i.e., get mail delivered), I have a clear conscience on that.

And while we're at it, please avoid the flames over Rabid Rerouting of
!-paths, either General RR or my much more restricted Domain
Absolutist version; again, it works, and we've gone over that ground
at least twice in the last year or so.  The only known failure case
was fidonet.org, and that has been resolved.

--karl