On Tue, Apr 15, 2014 at 10:57:37AM -0400, Christopher Browne wrote:
> Here is an announcement of a "block Yahoo users" policy just implemented by
> another free software project (
> http://lists.roaringpenguin.com/pipermail/remind-fans/2014/003025.html)
> which seems to sum the issue up briefly but accurately.

One alternative to this is to rewrite the From: address of Yahoo users
when they enter the list, adding .invalid to the end of the mail
address.  The resulting lookup for the DMARC record then looks in
(say) yahoo.com.invalid.  You can't respond to such users, of course,
and it may cause a lot of bounces, but fortunately .invalid is
guaranteed not to work anywhere so at least the DNS lookups will be
quick.

I do encourage people who are using yahoo and who want to use mailing
lists to ditch the yahoo account, however.  I also urge everyone to
avoid yahoo as much as possible, because I think this behaviour was
irresponsible and hostile to the Internet, and deserves to be shunned.

A

-- 
Andrew Sullivan
ajs at crankycanuck.ca