Al has some really good advice on how to fix discussion lists to work with the new Yahoo policy.
One thing I would add is the suggestion to actually check dmarc records before assuming policy. This will not only mean you’re not having to rewrite things that don’t need to be rewritten, but it will also mean you won’t be caught flat footed if (when?) other free mail providers start publishing p=reject.
Yahoo mail turns 16 today, and in celebration Yahoo is giving all their mail users presents.
Read MoreDMARC stands for Domain-based Message Authentication, Reporting and Conformance. What DMARC does is allow domain owners to publish policy statements in DNS telling receiver domains what to do with messages that do not authenticate. In addition, DMARC introduces the concept of “domain alignment.” What this means is that the authentication has to be from the same domain (or a sub-domain) as the address in the header-from: line. The idea behind DMARC is that organizational owners can use SPF and DKIM authentication to authenticate their actual domain in the header-from line. This moves authentication from a important but behind the scenes technology out to an end user visible technology.
Read MoreSpamhaus wrote about the return of open relays yesterday. What they’re seeing today matches what I see: there is fairly consistent abuse of open relays to send spam. As spam problems go it’s not as serious as compromised machines or abuse-tolerant ESPs / ISPs/ freemail providers – either in terms of volume or user inbox experience – but it’s definitely part of the problem.
I’m not sure how much of a new problem it is, though.
Spammers scan the ‘net for mailservers and attempt to relay email through them back to email addresses they control. Any mail that’s delivered is a sign of an open relay. They typically put the IP address of the mailserver they connected to in the subject line of the email, making it easy for them to mechanically extract a list of open relays.
We run some honeypots that will accept and log any transaction, which looks just like an open relay to spammers other than not actually relaying any email. They let us see what’s going on. Here’s a fairly typical recent relay attempt: