If you’re having trouble sending emails to any of the following Outlook’s domain names:
or having problems sending emails to Office 365 recipients, then it’s most likely that your IP has been blacklisted by Outlook (Microsoft), and you will need to get it delisted before your emails can reach any Outlook or Office 365 users.


Before you begin, be sure to investigate the reason why your IP (or IPs) got blacklisted in the first place.

A good place to start would be to Blacklist Check your IP and domain/hostname, to make sure it is not blacklisted on other public RBLs. If the IP/domain is blacklisted anywhere else, make sure to handle those delistings first, before you apply for delisting at Outlook.

First and foremost, before proceeding with any delisting procedures, make sure to fix the issues that got you blacklisted in the first place. This step is extremely important, and if you do not fix the issue that got you blacklisted, you’ll just end up being blacklisted again shortly after getting delisted.


In order to ask Outlook for delisting your IP address, you’ll first need to access these links:

Carefully read and submit the form located at the links above.

It may take the Outlook delivery support team a while to get back to you with an answer on your request, so it’s very important to be patient.


Please note that Outlook uses their own private blacklists, which nobody outside of their organization can access or query or run blacklist checks on. This basically means that HetrixTools cannot monitor or blacklist check the Outlook blacklists for you.