An important first step to make sure email sent from your IP isn't blocked is to review its status on known 'blacklists'. Instructions on this are available in our article: Determining if a server is blacklisted: https://kb.iweb.com/hc/en-us/articles/230267148-Determining-if-a-server-is-blacklisted.
You should also verify your server's mail queue content or outbox (current size and outbound email traffic statistics) to identify unusual activity levels.
Follow these instructions to unblock your IP from Hotmail / Outlook:
1. Ensure Compliance: https://mail.live.com/mail/policies.aspx
2. Follow best practices and FAQs: http://postmaster.live.com/Troubleshooting.aspx
3. Configure your reverse DNS on your IP addresses: https://kb.iweb.com/hc/en-us/articles/230242968-Configuring-Reverse-DNS-Control-Center-or-Customer-Hub-
4. Configure your SWIP (Shared Whois Project) information on your IP addresses: https://kb.iweb.com/hc/en-us/articles/230242948-Whois-Records
5. Configure your Sender Policy Framework information on your IP addresses: https://kb.iweb.com/hc/en-us/articles/230245188-Adding-SPF-records-to-domains
6. Join the Junk Mail Reporting Partner (JMRP) and Smart Network DataServices (SNDS) program: https://kb.iweb.com/hc/en-us/articles/230267648-Subscribing-to-Microsoft-JMRP-and-SNDS
Once other steps are done, please fill the Sender Information Form to send your removal request from Hotmail/Outlook blacklist.
You will receive an email from Microsoft postmaster support. Please follow the additional instructions provided by Microsoft. Further details can be found in this PDF document, released by Microsoft: http://download.microsoft.com/download/e/3/3/e3397e7c-17a6-497d-9693-78f80be272fb/enhance_deliver.pdf
In you need assistance, we invite you to contact our technical support department: https://kb.iweb.com/hc/en-us/articles/230242588-Opening-a-Customer-Service-Ticket