People who administer and participate in email discussion lists have been experiencing giant hassles in the past few weeks after Yahoo – and later followed by AOL – implemented aggressive DMARC policies without any advance warning.

DMARC is an emerging method of email authentication used to combat spoofing and allows domain owners to insist that any mail that has their domain address in the "From" line of the message must come directly from their mail servers. By changing its DMARC policy to p=reject, Yahoo and AOL directed receiving mail systems to reject messages that don't conform to these requirements.

This becomes problematic for all legitimate email discussion lists, not just those hosted on LISTSERV software, because they may be configured to have the original sender's email address in the "From" line, but since the email is distributed by the mailing list, DMARC-compliant mail systems will reject the message and bounce it back to the mailing list server.

All of a sudden, messages from subscribers with Yahoo email addresses stopped getting distributed, and even worse, innocent subscribers at other domains were getting auto-deleted from lists because they were rejecting and bouncing the Yahoo messages, as directed by Yahoo's DMARC policy, back to the list's bounce-handling address.

A variety of circumventions have been proposed by list owners, ranging for booting all Yahoo and AOL addresses off the list to putting the list address in the "From" field, with the potential side-effect of causing private replies and out-of-office messages to be distributed to the entire list.

On April 25, L-Soft introduced the industry's only seamless solution to the DMARC problem by releasing LISTSERV 16.0-2014a. The solution does not require anyone to make compromises or lose any functionality – not even the Yahoo and AOL subscribers. Incoming Yahoo and AOL addresses are automatically rewritten to local addresses that can receive private replies and forward them to the original poster.

For more information, visit:
http://www.lsoft.com/news/2014/listserv160-2014a-us.asp

To download LISTSERV 16.0-2014a, visit:
http://www.lsoft.com/download/listserv.asp