Seems they will continue to block us. The solution would be to get a dedicated IP from mailgun, but that costs 79 $/month, significantly more than ClojureVerse currently costs to run.
We have completed reviewing the IP(s) you submitted. The following table contains the results of our investigation.
Not qualified for mitigation
Our investigation has determined that the above IP(s) do not qualify for mitigation. These IP(s) have previously received mitigations from deliverability support, and have failed to maintain patterns within our guidelines, so they are ineligible for additional mitigation at this time.
Please ensure your emails comply with the Outlook.com policies, practices and guidelines found here: http://mail.live.com/mail/policies.aspx.
To have Deliverability Support investigate further, please reply to this email with a detailed description of the problem you are having, including specific error messages, and an agent will contact you.
Regardless of the deliverability status, Outlook.com recommends that all senders join two free programs that provide visibility into the Outlook.com traffic on your sending IP(s), the sending IP reputation with Outlook.com and the Outlook.com user complaint rates.
Junk Email Reporting program (JMRP) When an Outlook.com user marks an email as “junk”, senders enrolled in this program get a copy of the mail forwarded to the email address of their choice. It allows senders to see which mails are being marked as junk and to identify mail traffic you did not intend to send. To join, please visit http://support.msn.com/eform.aspx?productKey=edfsjmrpp&page=support_home_options_form_byemail&ct=eformts.
Smart Network Data Services program (SNDS). This program allows you to monitor the ‘health’ and reputation of your registered IPs by providing data about traffic such as mail volume and complaint rates seen originating from your IPs. To register, please visit http://postmaster.live.com/snds/.
There is no silver bullet to maintaining or improving good IP reputation, but these programs help you proactively manage your email eco-system to help better ensure deliverability to Outlook.com users.