I have been reorganizing my data yesterday, and as result created this list of domains grouped by their MX servers. It comes handy when configuring mta. This list is in no way complete and mostly reflects my UK data. I'll update it in time, and if anyone has something to add, please post it here. AOL aol.com aol.co.uk aim.com Yahoo Amerian MXs: yahoo.com yahoo.com.au yahoo.co.nz rocketmail.com ymail.com y7mail.com Europe's MXs: yahoo.co.uk sky.com yahoo.ie mx2.sbcglobal.am0.yahoodns.net sbcglobal.net nvbell.net wans.net TNZ MXs xtra.co.nz mx-rogers.mail.am0.yahoodns.net rogers.com mtaq1.groups.a03.yahoodns.net onelist.com mx-biz.mail.am0.yahoodns.net structcon.com gravelroots.net omotade.com tiggersabout.com newyorkmarinecadets.org byte2read.com potterhousegiftshop.com Hotmail hotmail.com msn.com live.com outlook.com live.co.uk hotmail.co.uk missing one mx record British Telecom btconnect-com.mail.eo.outlook.com btconnect.com mx.bt.lon5.cpcloud.co.uk btopenworld.com talk21.com btinternet.com TalkTalk Group mx-c1.talktalk.net talktalk.net mk-inboundfilter MXs uwclub.net dsl.pipex.com homecall.co.uk mxgb1.opaltelecom.net tiscali.co.uk lineone.net tinyworld.co.uk Wanadoo/Freeserve/Orange *.wanadoo.co.uk orangehome.co.uk *.freeserve.co.uk Mail.com mail.com Apple mac.com me.com KCOM Group eclipse.co.uk BigPond telstra.com bigpond.com Prodigy pacbell.net swbell.net snet.net ameritech.net prodigy.net flash.net P.S. I on purpose didn't include many of Yahoo's domains, so not to make this list unnecessary bulky.