What I finally decided to do was to put all Yahoo subscribers in moderated status, then post this message to our list:

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We are having an unusual problem with messages posted to the PPML by our Yahoo subscribers, and we have had to set all Yahoo subscribers to moderated status in order to be able to cope with it.

All messages posted by Yahoo users to mailing lists are now being rejected by a few service providers, mostly webmail providers. This is because Yahoo has implemented policies that cause mailing list messages sent by their users to be seen as as not meeting authentication standards. A recent message to the PPML from a Yahoo subscriber generated failed delivery notifications to us for 213 of our subscribers using providers such as Hotmail, MSN.com, Comcast, Yahoo itself, and many others.

If messages posted by our Yahoo subscribers come to us for moderation, I believe that what we will do is edit the message in order to make it acceptable to the service providers who are rejecting messages, then forward them to the PPML under our own email addresses.
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Or as I explained it to one of my co-listowners: "My thinking is to just select the text of their post, paste it into the text of a new message, and send this to the list using my own email address, prefaced with "forwarded on behalf of Yahoo user [name]" in the text area of the message. Absolutely no Yahoo header stuff, except for the subject of the message. "

I don't have a full technical understanding of the Yahoo problem, but hopefully my simplified explanation of it to our subscribers is sufficiently adequate.

I think this solution will work for our list, which is kind of in the doldrums at the present time, not many messages being posted. Before putting all our Yahoo subscribers (about 140 of them) in moderated status, I checked to see which of them are already in that status, so I can reapply the status if and when the Yahoo problem is resolved.

Charles Clausen
Prostate Problems Mailing LIst

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