If your sender score check out (80+), and everything else looks good, use the Microsoft deliverability form to contact their postmaster team - Hotmail Blacklist
I keep the current link in that discussion since it sometimes moves to a new page.
It is a VPS so I don't know if it is dedicated or not.
The green line looks like in September it dipped below 80 and then now at 82.
The volume spiked in mid September and I think this is because I was messing with IMAP and was moving lots of mails up and down, not sure if this affects it....
Or it is possible one of the e-mails from an employee was compromised.... we did get a warning about high volume sending...
MS just denied us for unknown reason.
But I see that we've had in the past month crazy amounts of mails sent from one single infected e-mail and this is resolved so.... hard to believe, I replied to MS begging them to let our mails through... This is crazy....!!!
Thank you so much for helping!!!
After much begging, explaining, etc. finally we are unblocked! MS thought we were a marketing company or something. I had to explain when did it happen (exact date), how did it happen and what did we do to correct it.... 3x!!! 2x rejected!!!
So, now on our online program where customers enter their e-mail, we have put in a notation to avoid MS mails and use something else like Gmail.... @popowich, thank you again for your help!!
That happens a lot, you will get spam bots that will just enter a lot of bogus emails address, I run a few forums and I see this happened quite a few times on different sites of mine. The best way to combat that is to put google's captcha code on your registration page, they have a new captcha that just requires a checkbox, so it's not horrible anymore. Checking your sender score is a good idea, but you should also use a blacklist monitoring service for your domain and IP to be notified when they appear on a public blacklist.