[TowerTalk] Bounces

Wes Attaway (N5WA) wesattaway at bellsouth.net
Mon Apr 14 22:30:59 EDT 2014

What I don't understand is why contesting.com can't get on the "approved
list" for the yahoo.com mail servers.  It seems to me that this problem
could be resolved by old fashioned phone call, or maybe even a (gasp)
letter, or even a personal visit between two admins.

Wes Attaway (N5WA)
318-393-3289 - Shreveport, LA
Computer/Cellphone Forensics
EnCase Certified Examiner

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Al
Sent: Monday, April 14, 2014 3:36 PM
To: TT TowerTalk
Subject: Re: [TowerTalk] Bounces

DMARC incorporates forms of spf.and dkim.  The latter uses a digital
signature while the former uses a DNS hack to verify that the server
originating an email address is actually authorized to send mail on behalf
of that domain.  The main problem with both is that if not universally
implemented for sending domains, you either let through a lot of spam (if no
spf, allow delivery) or you bounce a lot of legitimate emails (if no spf,
deny delivery) from false positives.  A hybrid rule if you elect for the
restrictive policy is to allow delivery if an spf policy is missing if the
sending server has the same IP address as the mx record in DNS for the
sending domain, which really only works for relatively small organizations.

Unfortunately, there is no real solution as Gary has noted.  Yahoo would
have to publish a policy that says contesting.com servers are allowed to
send emails on behalf of yahoo.com.  Ain't. Gonna. Happen.  And this problem
potentially goes well beyond Yahoo.  Any system implementing spf or dkim in
a strict implementation will exhibit the same behavior. 

An alternative is for contesting.com to send out email as FROM:
xxxxx at contesting.com.  The downside is that it becomes impossible to reply
to the originator, only the reflector.  But yahoo.com emails would not


From: TowerTalk [towertalk-bounces at contesting.com] On Behalf Of GARY HUBER
[glhuber at msn.com]
Sent: Monday, April 14, 2014 3:19 PM
To: TT TowerTalk
Subject: [TowerTalk] Bounces

Here is what I received from a reflector administrator yesterday....

Yahoo introduced a feature (DMARC) this week that basically says "If a
message has a yahoo.com email address as the FROM address, and it didn't
come from a Yahoo.com server, then it's not acceptable."

This policy is not compatible with mailing lists.  List messages all go out
with the email address of the person that posted the message.  If the
person posting is using an @yahoo.com email address, the message goes out
with FROM: xxxx at yahoo.com.  This message is sent from the mailing list
server  and not from Yahoo.com's servers...
therefore Yahoo is not accepting these messages.

It's a little complicated, but this policy is also causing other members to
get unsubscribed due to bounces.  Other providers are now bouncing these
messages, because Yahoo has basically instructed them to do so.  You may
have already received some mail from our list, asking you to reconfirm your
subscription.  It is because of this issue, caused by yahoo.com users
posting to our list.

You can read more about it here:
And here: http://www.ietf.org/mail-archive/web/ietf/current/msg87153.html

The second link suggests that to fix this problem we need to:

* Suspend posting permission of all yahoo.com addresses, to limit damage.
* Tell Yahoo users to get a new mail account somewhere else, pronto, if
they want to continue using mailing lists.

I am going to ask the Board to consider these options.  This email is
mainly a heads up to yahoo.com email users that changes are a brewing and
you should be looking into other options for your mailing list mail.

One idea for yahoo.com users:  Consider using a free email forwarder from
arrl.net  and have it forward to your yahoo.com address.
Subscribe to the  list with your arrl.net  address, then
configure your email program to send from your arrl. email
address when you post to the (and other) mailing list.  Another idea
would be to move to a different free email provider, such as GMail.

73 & DX,
Gary - AB9M

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