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DMARC is an anti-spam system that makes rigorous checks on the domain of received email.
Yahoo has set their DMARC policy to “reject”, so any mail that is suspicious is rejected instead of delivered. It seems that they trust email sent from their own domain, so bounces from Yahoo email addresses never happen for Yahoo Groups.
It seems that Yahoo’s DMARC will sometimes accept email from a groups.io
group and sometimes not. When it rejects the email, the user is unsubscribed because the mail bounced.
Nearly all other providers use a policy of “quarantine”, which accepts the mail but puts it in a spam folder. That policy does not cause this problem.
Other providers with a “reject” policy are AOL and Mail.ru
http://observer.wunderwood.org/ (my blog)
On Mar 19, 2018, at 11:56 PM, Dave Sergeant <dave@...
I understand all this, but why do Yahoogroups, Google Groups and all my
other various email list providers continue to work well without having
this automatic unsubscribe? Why have groups.io
to do it but everybody
else can seem to manage without having to do anything similar?
On 20 Mar 2018 at 5:28, toki wrote:
On 03/19/2018 11:12 PM, Barbara Byers wrote:
Is this a real negative or just speculation of what "might" happen?
It is a very real threat. Furthermore, it is something that can easily
escalate up to a plethora of email vendors, even if they don't implement
Here is how it escalates.
AOL member sends the list mail to the spam bucket. Member then deletes
the message. AOL sends FBL to Groups.IO. Mark ignores it. Member
receives a second message, which is tossed into the spam bucket, then
deleted. Cycle repeats itself ad infinitum.
At some point, AOL's anti-spam bots kick in, and blacklists Groups.IO as
a spammer. A week or two passes, and the email from groups.io hasn't
decreased, so the AOL anti-spam bots escalate the listing up to one of
their upstream RBLs. The RBL adds it to their list, and wham. A small,
but significant number of ISPs start rejecting Groups.IO mail. And since
Groups.IO ignores the FBL, these ISPs escalate to their other RBLs. And
six or so month later, Groups.IO is on everybody's RBL, with no way to
Caveat: I don't know if AOL is as diligent in stopping spammers now, as
it was in its heyday. (Now wondering if AfterBurner was at AOL, or
another site that was frequently considered to be a spam-haven.)