Administrative Note: Users of yahoo mail

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

Recently yahoo.com and its related domains (ymail.com, yahoo.ca, yahoo.fr,
yahoo.co.uk, etc.) began publishing something called a DMARC record.  The
purpose of a DMARC record is to identify the servers that send the email
of yahoo users.

As part of the DMARC publication, the record may assert that *only* those
servers are allowed to send email for yahoo users.  Receiving servers who
agree to participate in the DMARC process, such as Gmail, may choose to
reject mail from yahoo users that does not come from one of those servers.
Yahoo has chosen to make this assertion in their published records.
This is intended to prevent phishers and spammers from masquerading as
yahoo users, a problem which has been widespread for a while now.

What this also means, mostly by accident, is that if you are a yahoo user
and you send a message to a mailing list such as zsh-users, then when the
mailing list server forwards your message to the list recipients, it looks
as if the message has not been sent by a yahoo server, and therefore some
receiving servers will reject it.

In short, if you send mail to zsh-users from yahoo, your message will not
reach the entire list.  Disclosure:  brasslantern.com is hosted at google
apps, so I am one of the people who will not see your message.

Internet standards groups are discussing workarounds for this, but it may
be several months before anything is resolved and much longer before any
necessary changes are made to mailing list software, etc.  In the meantime,
you should be aware that using yahoo for anything other than yahoo-hosted
groups is likely to result in missed messages.