Incoming SMTP in the year 2017 and absence of DKIM

John Levine johnl at
Wed Nov 29 22:50:16 UTC 2017

In article <3677d101-3874-b8e4-87b3-37e4dd870325 at> you write:
>> Normal lists put their own bounce address in the 
>> envelope so they can handle the bounces, so their own SPF applies.
>Yep.  V.E.R.P. is a very powerful thing.  (B.A.T.V. is an interesting 
>alternative, but I never messed with it.)

VERP helps identify the bouncing party, but list bounce handling works
fine without it.  What matters is that it's the list's address in the
envelope, not the message author.  BATV works OK (I should know, I
invented it) but it has its false positives.

>I'm saying that I've heard arguments over the last 15 years from people 
>that (FC)rDNS and SPF (independently) are things that will break some 
>portion of email.

Broken rDNS is just broken, since there's approximately no reason ever
to send from a host that doesn't know its own name.  Broken SPF may or
may not be an issue since there are lots of legit ways to send mail
that SPF can't describe.


>P.S.  I'm strongly of the opinion that if a MLM alters the message in 
>ANY capacity, that it is actually generating a new message.  Thus the 
>MLM is the new author.  It's just using content strongly based on emails 
>that came into it.  -  But that's a different discussion that lasted 
>days on the mailman mailing list.

It's an interesting theological argument but it makes little practical

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