[tsc-devel] [ANN] Yahoo email addresses are incompatible with mailinglists

Marvin Gülker | Sat, 04 Nov 2017 20:21:49 UTC

Hi everyone,

I wanted to make everybody aware that email addresses issued by Yahoo!
are incompatible with mailinglists in general, and with tsc-devel (and
tsc-users) in particular. You will not receive any emails from the
mailinglist if you have a Yahoo! email address.

The reason for this is a spam-fighting technology named "DMARC" which
effectively labels all mailinglist emails as spam. If you are not into
the administration of email servers, the topic is difficult to
understand, but the essence is that because discussion mailinglist
servers modify relayed email (changing the subject and appending
footers), the modified email fails to pass the DMARC spam check. Yahoo!
has configured their webservers with a DMARC policy named "p=reject",
which means that mails failing the DMARC check are rejected by the
mailserver. Further information can be found on the following web pages:

* https://thehackernews.com/2014/04/yahoos-new-dmarc-policy-destroys-every.html
* https://en.wikipedia.org/wiki/DMARC

Since Yahoo! has suffered heavy security breaches recently and has been
completely bought and mostly ended by Verizon[1] I see no reason to
engage into stupid DMARC mitigation as suggested by some
sources[2]. Since Verizon may terminate the rests of Yahoo! anytime
anyway, you should simply move away from it.

There may be other mail services than Yahoo! which use a DMARC policy of
"p=reject", but they are rare enough I've never seen them; most likely
this affects some corporate email servers. With Yahoo!'s decline, there
is no notable defender of "p=reject" DMARC left.

I'm going to update Mailman's configuration to reject subscription
requests from domains protected with DMARC "p=reject" policy.

Marvin

[1]: https://en.wikipedia.org/wiki/Yahoo!#Decline.2C_security_breaches.2C_Verizon_purchase
[2]: https://wiki.list.org/DEV/DMARC

-- 
Blog: https://www.guelkerdev.de
PGP/GPG ID: F1D8799FBCC8BC4F
_______________________________________________
tsc-devel mailing list -- …l@l…
To unsubscribe send an email to …e@l…