Run an email discussion list? Here's how to deal with DMARC

Yahoo's recent DMARC policy changes have made it so that Yahoo subscribers will now have trouble participating in old fashioned LISTSERV-style discussion lists. When a Yahoo user posts to your discussion list, very few subscribers will receive that message, because any ISP that respects DMARC policy will bounce that message. (And I believe that at least half of the top ten mailbox providers in the US now respect DMARC policy.)