Hello folks.

I was making noises a few months back in reference to this. I did some
experimentation with TCP tables (not the first time) and wrote one for
purpose. The actual Trualias implementation came with too much baggage
for my tastes, so I created a new base server which I offer to anyone
who wants / needs a reference implementation in Python:
https://github.com/m3047/trualias/blob/fwm/python/BASE_SERVER_README.md

The server I wrote installs as a smtpd_sender_restrictions +
check_sender_access filter so that it gets the full envelope sender as
the query. It performs three actions:

1) Checks a white / allow list.

2) Checks a remap list, which rewrites domains to be validated as other
domains.

3) (Finally) does an MX lookup for the domain, and checks a list for the
resulting hosts. E.g. if an MX lookup for spammybank.com or
cityofmuppets.org returns mxa-00103102.gslb.ppexample.com, then it's
possible to match *.ppexample.com and return something like "REJECT
Blocked by ppexample.com"

All three lists support wildcards with label semantics in key values.
External dependencies have been minimized in the spirit of LOTL
(primarily dnspython). 100% ape-crafted, with care. An example of the
lists' semantics is at the bottom of this article:
http://consulting.m3047.net/dubai-letters/blocking-esps-play-nice.html

Send me an email and tell me all about Ned, and I'll send you my actual
implementation script.

--

Fred Morris, internet plumber


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