Microsoft Blacklists

Microsoft uses its own blacklists to filter emails by IP address. As far as we know, only Spamhouse is taken into account when forming these black lists.

Microsoft uses 2 blacklists for different platforms. The first for Outlook, Hotmail, Live and MSN. The second is for Office365.

If You Receive an Error Message from Microsoft

  1. Find in the message the information on which blacklist contains the sender's address.
  2. Check if your server is sending spam.
  3. Make sure your server's IP address is not on any blacklists.
  4. Make sure that emails sent from your server comply with Microsoft's policies and guidelines.
  5. You can start removing your server's IP address from the blacklist.

Removing From Outlook, Hotmail, Live, MSN Blacklist

If the IP address of your server is in the first Microsoft blacklist, you will receive an error message like this:

Error message about Microsoft blacklist

  1. Complete the following fields on this form on the Microsoft website:
    1. Title of the problem description - for example, error sending to,
    2. Contact name - your name,
    3. What is the recipient's domain - select one of the options,,,
    4. Email address of the contact person - enter a valid address, a reply will be sent to it,
    5. What is the sender's domain - specify the domain from which letters are sent,
    6. How would you describe your company or yourself - choose one of the options (university, company, etc.),
    7. Outgoing IP addresses or ranges - use semicolons to separate IP addresses or ranges, for example; yyy.yyy.yyy.yyy or; yyy.yyy.yyy.yyy/28.
    8. You have a dedicated or shared server - select an option from the drop-down list,
    9. Copy and paste all error messages - for example "Remote Server returned: '550 5.7.1 Unfortunately, messages from [] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3140)." 
  2. You will receive an automatic reply within 12 hours. There are 2 possible answers:
    1. Mitigated - The IP address has been removed from the blacklist.
    2. Conditionally mitigated - the IP address has not been removed from the blacklist.
  3. If the IP address has not been removed from the blacklist, reply to the letter you received and ask for more information about the reason for blocking.
    When you first contact (when filling out a form on the Microsoft website), you receive an automatic response from the bot. When replying to this letter, your request will be considered by a company employee. Typically, employees manually remove an address from the blacklist.
  4. An employee can refuse to remove an address from the blacklist. The answer might be:
    "Dear Sender, We have completed the verification of the IP addresses you provided.
    Here are the results of our test: Not suitable for unlocking Our investigation has determined that the above IP addresses are not eligible for unblocking. Make sure your emails comply with the policies and guidelines outlined here:"
  5. Reply to this letter asking for a more detailed investigation. Write that your emails are fully compliant with Microsoft policies and guidelines.
  6. In a few hours you will receive a message:
    "My name is Deepthi and I work for support. We will look into this issue shortly.
    IP: We understand the urgency of this issue and will provide information as soon as it becomes available. Your request is being tracked and we will contact you as soon as we have more information."
  7. Be sure to reply to this letter. For example, "Thank you, I am waiting for the results of your work."
  8. Continue to communicate on this request until you receive the following message:
    "Hi, My name is Sai and I work for support. Recent activity from your IP ( has been flagged as suspicious by our system and as a result your IP has been blocked. I have investigated sending email from your IP and removed the block. This process can take 24-48 hours."
  9. Write "thank you" and save your entire message history. This may help you in the future. Microsoft may blacklist you again for no reason.
  10. If the employee refused to remove your IP address from the list, the hosting company can confirm it. To do this, inform a Microsoft employee about it. Then a request will be made to confirm the IP address to the hosting company, which will have to confirm this information.
  11. If the IP address is not removed from the blacklist even after it has been confirmed by the hosting company, you can change it. To do this, contact technical support.

Removing From Office365 Blacklist

If your server's IP address is on the second Microsoft blacklist, you will receive an error message like this:

Option 1 

Second error message
  1. Click on the first link in the error message and fill out the form.
  2. Click on the second link provided in the error message and follow the instructions.
  3. After that, the IP address of your server should be removed from the blacklist. 

Option 2

Error message

  1. Write a letter to the address indicated in the message
  2. In response, you can receive:

Option A. Instructions to fill out the form and a link to this form. After filling out the form, the address will be removed from the blacklist.

Option B. The message is as follows:

Error message

  1. Make sure no spam is being sent from your server.
  2. Resend your email to the address provided in the email.
  3. If the message states that your address is not on the black list - send the last error message to this address.
  4. If you are sure that spam is not sent from your server, and the above actions did not lead to the removal of the address from the black list, contact technical support

Microsoft E-mail Monitoring Software

Microsoft offers free programs for Outlook (except Office365): SNDS and JMRP. They do not allow you to remove an address from the blacklist. They are designed to monitor and analyze your IP address traffic. The main goal of these programs is to improve the deliverability of emails to users of Microsoft products.

SNDS (Smart Network Data Services)

SNDS provides traffic and complaint data for emails sent from your server's IP address. The data is provided only if more than 100 letters are sent from the IP address per day (only Microsoft accounts are taken into account as addressees).

In order to use SNDS, you must register using the link. Request authorization of addresses to be monitored. To verify the owner of the IP address, Microsoft uses 2 methods at the same time - WHOIS and rDNS. You can send an email to your domain. If this is not possible, contact technical support.

JMRP (Junk Email Reporting program)

JMRP allows you to determine which of your emails are getting negative ratings from recipients. Microsoft sends copies of messages to the sender that are flagged as junk by recipients.

To use JMRP follow the link. Pre-monitored addresses must be registered with SNDS. JMRP sends a subset of emails marked as junk, rather than each email separately.