Certain people on technical mailing lists use e-mail addresses from providers, but refrain from routing their outgoing mail through those providers.
Technically, this is supposed to be allowed, at least by some operational subset of the RFCs for the internet.
But the result is that the providers have no opportunity to put their stamp of approval on their outgoing mail.
According to the current efforts to control unsolicited mass mailing ("spam"), lack of that stamp of approval is supposed to be(come) one of the principle marks of unsolicited mass mailing.
Once upon a time, the internet was supposed to be egalitarian. If I wanted to run my own e-mail servers, there was no particular reason for me not to. And if I wanted to run a mailing list or a news server, if I could afford a server, I could do it.
Somebody wants to say, "NO MORE! You have to be part of the establishment to do that!" (This, in the form of paying unreasonable fees to arbitrary self-declared bureaucracies who certify "identities" based on marginal documentation rather than actual knowledge or familiarity.)
I sometimes wonder if much of the unsolicited mass mailing industry has not been supported by people who didn't want that egalitarian internet. They want everyone to be brought under the umbrella of their Internet, where they control the licenses and privileges.
I've ranted about this before, as in this post: http://defining-computers.blogspot.jp/2014/05/things-to-fix-in-e-mail-newsgroups-and.html that is now out of date because the world has headed significantly in the opposite direction.
We have to get ourselves un-addicted to official approvals.
The blame lies elsewhere. I wish I had the network and social cred to
get a real movement started, away from the current faceless CA system and
towards a different identity assurance system that depends on actual, existing
day-to-day trust relationships.
Anyway, Tim, Gil, et. al., my spam box is about half full with your
conversations from Fedora mailing lists. The anti-Monsanto campaign gets
another tenth, to push the volume of false-positives over 50%.
This causes me mixed feelings, and a certain ironic amusement.