"I use a Yahoo.com address, and I have a problem with your mailing list. What's up?"

Over the weekend, Yahoo made some technical changes, the result of which is that it will be very difficult to participate in most mailing lists, including those I administer, with Yahoo e-mail addresses. You will need to use a different non-Yahoo address if you want to continue to receive or participate on this list. I’m sorry.

You might, or might not, receive messages from these lists. Other people almost certainly will not receive any messages you send to these lists. You probably won’t be able to subscribe to these lists — subscription confirmation messages will bounce.

This affects my “Practical Nomad” e-mail newsletter as well as several much smaller community and special-interest mailing lists I administer.

You will probably be removed automatically from most or all of these lists. You might, or might not, get notice that you have been automatically removed or that your subscription has been disabled.

If you use a Yahoo.com e-mail address and received a message from the list-robot at Hasbrouck.org yesterday or today, or receive a message in the future, about “too many bounces”, or about your subscription being “suspended”, that’s probably what it’s about.

I have nothing against people who use Yahoo mail (or AOL, which also blocks some e-mail in even less predictable ways).

This is not a result of anything I did, and there is nothing I can do about it. This is a result of a change Yahoo has made. In effect, Yahoo has given automated instructions to all other mail systems to reject mail from Yahoo addresses sent to mailing lists or sent in some other ways.

Here’s an analysis from my friend John R. Levine, a technical expert on spam, consumer advocate, and author of “The Internet For Dummies”:

“Yahoo addresses a security problem by breaking every mailing list in the world”

If you don’t like this, you as a Yahoo user can complain to Yahoo.

Here’s what Yahoo says about its new “system”, DMARC. Yahoo admits that no existing list management software works the way Yahoo expects every system that sends, receives, or forwards mail to or from Yahoo to act.

I use the “mailman” software. If mailman is eventually modified to easily support DMARC, I will try to find a way to get mail to and from Yahoo.

For the more geeky among you, here’s a thread about this from the mailman developers’ discussion list (which is itself affected by this problem).

[Update: An additional page about this issue has been added to the Mailman developments wiki: “DMARC is a standard developed as a technique to reduce email spam and phishing. Unfortunately, it has negative consequences for mailing lists, essentially breaking long established mailing list norms, standards, and behaviors. Yahoo! recently began publishing a DMARC policy for rejecting all messages that fail the signature tests, and every mailing list with Yahoo! members started seeing bounces from these members. This has caused the Mailman community of members, list administrators, and developers enormous pain. Mitigating the effects of the DMARC reject policy are difficult. All known mitigation techniques break some user expectations and/or degrade the user experience.” I have implemented some of the options in newer versions of Mailman, but these may not be effective and may cause other problems.]

You can subscribe yourself to my newsletter with a new address using the form in the sidebar or here.

If you are on one of the other e-mail discussion lists I administer at Hasbrouck.org, send me your new or alternate (non-Yahoo) address, and I’ll add that address manually.

I’m sorry, but this isn’t my fault or within my control.