(from https://en.wikipedia.org/?oldid=579580929#WMF_notification_email_marked_as_spam_by_Yahoo )
According to several comments, this means that our mail is currently blacklisted by Yahoo!, so it's sent in the "Bulk" folder for users who have it enabled (if not to spam?). WMF needs to send a "Bulk sender application for whitelisting" http://help.yahoo.com/kb/index?page=content&id=SLN9042 but first their guidelines have to be respected: http://help.yahoo.com/kb/index?y=PROD_MAIL_ML&page=content&id=SLN3435
There are several things in there that we don't do; let's add each of them to blockers when we're sure there's something to do.
* "Use email authentication such as DKIM": low-hanging fruit, let's do it as soon as possible (bug 56413).
* "Be CAN-SPAM compliant": it's USA law, I assume we're respecting it. :) It seems very lenient, from a quick skimming we're ok. http://business.ftc.gov/documents/bus61-can-spam-act-compliance-guide-business
* "Consistently manage your lists": no idea, but MediaWiki surely doesn't remove/disable addresses which bounce: I remember Brion mentioning this in some 2005 bug comment or something like that, I don't know if there's an open bug but I'd say it's something worth doing.
* "Segregate your mail streams by IP address and/or domain": in theory we do, I can't judge if well enough.
* "Using your domain consistently": no idea, is it consistent to send from firstname.lastname@example.org but then use @wikipedia.org, @mediawiki.org and so on to From headers etc.?
* "Publish reverse DNS (PTR) records for your sending IPs": looks ok.
$ dig -x 22.214.171.124
;; ANSWER SECTION:
126.96.36.199.in-addr.arpa. 3552 IN PTR wiki-mail.wikimedia.org.
* "Secure your mail servers": I hope so.
* "Use common-sense settings": it would be nice to track this (Ori, do you know something?), but Echo sends only few thousands notifications per day on en.wiki (https://toolserver.org/~dartar/en/echo/ ) and standard enotif (talk and watchlist) on all wikis is probably only one or two order of magnitudes bigger, it's still a ridiculously low amount of emails, we're not DoS'ing Yahoo!. It's possible that we have peaks, for instance an edit to a heavily watchlisted pages could cause a peak of thousands enotifs in a single second, but I doubt it's relevant. When we enabled enotifwatchlist on all wikis, the increased network activity of mchenry wasn't even visible at all in ganglia.