[Mailman-Users] ARC, was non-subscribers getting through--email address in "Real Name"

John R Levine johnl at taugh.com
Wed Jul 25 09:52:51 EDT 2018

> > As I said a few messages ago, if lists did more stringent tests on
> > incoming mail, a lot of this complexity could be avoided,
> I don't understand this.  If lists got a pass, every spam would grow
> RFC 2369 header fields.  No?

Large mail systems already know where all the mailing lists are.  It's 
obvious from the tags in the DMARC reports I get from Gmail.  The reason 
we have kludgy ARC rather than just whitelist list servers is that lists 
don't filter inbound spam, so ARC gives the recipient systems clues to do 
filtering retroactively.

If lists filtered better, e.g., by doing DMARC checks on INBOUND mail, 
that's checking INBOUND mail as it ARRIVES at list servers*, there'd be 
much less leakage and no need for retroactive filtering.

Nobody's going to whitelist on List-ID, they'll do it with IP addresses.

John Levine, johnl at taugh.com, Taughannock Networks, Trumansburg NY
Please consider the environment before reading this e-mail. https://jl.ly

* - PS to Stephen, I know you understand the difference but a lot of other 
people reading this clearly don't.

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