Microsoft mail / Outlook mail / Hotmail rejects all SMTP delivery attempts from address space that includes a server I administer, ks3282833, 5.39.95.159. Here is a recent Postfix log message:
Jan 19 22:16:49 s2 postfix/smtp[22719]: DBC925C0079: to=, relay=mx3.hotmail.com[65.54.188.72]:25, delay=1.7, delays=0.11/0.02/1.5/0.15, dsn=5.0.0, status=bounced (host mx3.hotmail.com[65.54.188.72] said: 550 SC-001 (BAY0-MC1-F25) Unfortunately, messages from 5.39.95.159 weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. (in reply to MAIL FROM command))
This server and its domains do not appear on any of the >100 public blacklists queried by
http://mxtoolbox.com/blacklists.aspx. Outgoing mail is correctly authenticated via SPF and signed by DKIM, both of which pass gmail verification. This server operates on dedicated IP addresses that are shared with no other entity. No other SMTP service we communicate with blocks our mail (including gmail). While some OVH hosts may be controlled by spammers, it is unreasonable to block everyone in a data center address block of static, dedicated IP addresses.
I have raised this with the "Microsoft community" without success. Can OVH attempt resolve this problem?
Bill Clay
Modena, Italy