If you find users being dropped from mailing lists, it's probably a DMARC issue. Contact your mailing list vendor for appropriate patches. https://wordtothewise.com/2014/04/brief-dmarc-primer/ A brief DMARC primer http://dmarc.org/overview.html DMARC Overview http://www.socketlabs.com/blog/yahoo-com-changes-dmarc-policy/ Yahoo.com Changes DMARC Policy http://yahoomail.tumblr.com/post/82426900353/yahoo-dmarc-policy-change-what-... Yahoo DMARC Policy Change - What Should Senders Do? http://yahoo.tumblr.com/post/82426971544/an-update-on-our-dmarc-policy-to-pr... An Update on our DMARC Policy to Protect Our Users http://www.lsoft.com/news/2014/listserv160-2014a-us.asp LISTSERV(r) Inventor Develops Seamless Solution to DMARC Hassles matthew black california state university, long beach -----Original Message----- From: NANOG [mailto:nanog-bounces@nanog.org] On Behalf Of Jared Mauch Sent: Wednesday, July 09, 2014 7:09 AM To: NANOG list Subject: hotmail email issues today? Anyone know what happened? I've started to see a large number of bounces from them (this caused a large number of people with their e-mail hosted there to be removed from mailing lists I host). Offlist replies/pointers to what I'm doing wrong are welcome. - Jared