I have a SMTP server on a Windows server 2008 R2. It can send messages to all other domains except the ones hosted at Microsoft (hotmail.com,outlook.com, etc). The email messages it cannot send remain in: \mailroot\Queue. Also the logs only show the following:
127.0.0.1, SERVERNAME, 4/25/2016, 15:13:13, SMTPSVC1, SERVERNAME, 127.0.0.1, 0, 9, 226, 250, 0, EHLO, -, SERVERNAME,
127.0.0.1, SERVERNAME, 4/25/2016, 15:13:13, SMTPSVC1, SERVERNAME, 127.0.0.1, 0, 27, 40, 250, 0, MAIL, -, FROM:<noreply@domain.com>,
127.0.0.1, SERVERNAME, 4/25/2016, 15:13:13, SMTPSVC1, SERVERNAME, 127.0.0.1, 0, 33, 36, 250, 0, RCPT, -, TO:<somename@hotmail.com>,
127.0.0.1, SERVERNAME, 4/25/2016, 15:13:13, SMTPSVC1, SERVERNAME, 127.0.0.1, 0, 50358, 141, 250, 0, DATA, -, <SERVERNAMEOlbpH71yEXUIEAO00000059@SERVERNAME.subname.domain.com>
Messages to gmail look exactly the same, except the destination is some hotmail/live/outlook address.
Ive also check my SPF records and they check out, else gmail wouldve already blocked the messages.