My company has recently purchased a VPS for email and webhosting. I am not an expert on email authentication but here is my story.
After the VPS was purchased we started receiving bouncebacks with the error message from hotmail.com:
550 SC-001 (COL0-MC1-F10) Unfortunately, messages from 18.104.22.168 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
After doing research on the issue I have tried to join hotmail Sender ID program. I also added an SPF to my domain (not sure if it is correct)
v=spf1 a mx ip4:205.234.20x.xx a:xxserver.com mx:xxserver.com ?all
After petitioning the Hotmail blacklist by filling out their form, I am still on their blacklist. Many of our customers are Hotmail accounts and this is becoming a big issue for us. I am not sure if my rDNS is correct, the SPF record or what is the problem.
I am aware that I may be leaving out some information, I am new to the email server administration so I will post what I can to make this easier. Thank you!
I have seen other threads on here and tried to follow their instruction to no avail.. and I did not want to resurrect an old thread.