> I have asked them to uniquely identify sending accounts with some > custom header / token, to empower mailbox operators to filter that > stream of sewage and deal with it differently from the other, higher > value streams that are commingled in their stream.
You're asking for something that is already there. It's in the envelope-from. Here's a few very recent samples. <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> If there is a plus: The first 6-digit hex number after "bounce+" and possibly after "v2+" is the customer ID. If there isn't: The entire envelope-from is. As for dealing with Mailgun: Applying your rules to whichever IP addresses AS396479 announces deals with a very large majority of what Mailgun are sending. There are still legacy netblocks they are using within Rackspace ASes (19994, 27357 and 33070 at least), also Mailjet (which they bought in 2019) is still sending out of its own AS (200069), and some of Mailgun's networks are actually announced by Amazon's AS16509. -- Atro Tossavainen, Founder, Partner Koli-Lõks OÜ (reg. no. 12815457, VAT ID EE101811635) Tallinn, Estonia tel. +372-5883-4269, https://www.koliloks.eu/ _______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
