I have a Linux VPS and I installed postfix to send emails from it.
Gmail working fine. But hotmail.com, outlook.com do not accept the emails, even to the Spam/Junk folder.
The log says something like:
host mx3.hotmail.com[65.55.92.136] said: 550 SC-001 (SNT004-MC1F14) Unfortunately, messages from XX.XX.XX.XX 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)
After lots of search and efforts I came across to Sender Information for Outlook.com Delivery form. I filled it up and sent.
While after, I got an email from Microsoft Support which gave me good news!
The emails I sent from the VPS started to be delivered to hotmail! Hurray! :)
Here is the part of the email I got:
We have completed reviewing the IP(s) you submitted. The following table contains the results of our investigation.
Conditionally mitigated
XX.XX.XX.XX
Our investigation has determined that the above IP(s) qualify for conditional mitigation. These IP(s) have been unblocked, but may be subject to low daily email limits until they have established a good reputation.
Please note that mitigating this issue does not guarantee that your email will be delivered to a user’s inbox.
Ongoing complaints from users will result in removal of the mitigation.
Mitigation may take 24 - 48 hours to replicate completely throughout our system.
If you feel your issue is not yet resolved, please reply to this email and one of our support team members will contact you for further investigation.