Yahoo began imposing a stricter email validation policy that breaks the usual workflow on legitimate mailing lists, an email expert says. The new policy is advertised by Yahoo to third-party email servers. Users of Gmail, Hotmail and other DMARC-enabled providers will not only fail to receive messages sent to the mailing list by Yahoo users, but will flood the list with bounce messages, risking to be bounced off the list themselves. An email expert recommends that mailing list operators suspend the list posting rights of yahoo.com users and ask them to re-subscribe to their lists with accounts from different email providers.”]
Source: https://www.csoonline.com/article/2141462/yahoo-email-antispoofing-policy-breaks-mailing-lists.html