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Hotmail Blacklist

Did Hotmail block your email?

If so, you are not alone.

While Hotmail email blocks are undoubtedly frustrating, they are simpler to resolve than other email blacklists.

Using our 5 step process, you can remove your IP from Hotmail’s email blacklist. 

We have a 100% success rate using this process. Most removals take 3-5 days.

TL;DR
Make sure your server is not sending spam, that you authenticate your email, and then submit the Hotmail Blacklist Removal Form.

Hotmail Blacklist Check

Before digging into the removal process, make sure your email is blocked.  Unlike public email blacklists, Hotmail does not provide a direct lookup tool. Microsoft does provide IP feedback through its sender services, but that requires signing up.

The easiest way to check if you are on Hotmail’s blacklist is to send an email. If your Hotmail blocks your email, you receive this bounce notice:

<someone@hotmail.com>: host
hotmail-com.olc.protection.outlook.com[104.47.6.33] said: 550 5.7.1
Unfortunately, messages from [192.16.1.1] weren't sent. Please contact
your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [VE1EUR02FT003.eop-EUR02.prod.protection.outlook.com] (in reply to MAIL FROM command)

If you do not get a bounce, your email may be routed to the spam folder.  The process below is for removal from the Hotmail or Outlook blacklist only.  Do not complete this if you are not seeing bounces.

Microsoft’s Email Domains

Microsoft has several domains, but they all use the same blacklist.

  • hotmail.com
  • live.com
  • outlook.com
  • msn.com

There are also country-specific versions of these domains, such as hotmail.co.uk. The Hotmail blacklist removal process works for them also.

Hotmail Blacklist Removal Process

1. Why Does Hotmail Reject Emails?

If Hotmail is rejecting emails, they have detected unwanted activity from your server. While there are many reasons that Hotmail may block your email, the most common reasons are:

  • Your email volume changed significantly or quickly.
  • You are sending emails from a new IP address.
  • You are sending email to unknown users.
  • There is spam originating from your server
  • Your Email Authentication fails
  • Your DNS is incorrect.

Finding the Problem

You need to dig into your server’s logs to find out why Hotmail blocks your emails.

You can search for these strings in your email logs:

protection.outlook.com
http://mail.live.com/mail/troubleshooting.aspx
list (S3150)

Generally, one of these snippets is in the log error showing the bounce.

Look for the first time that Hotmail or Outlook.com blocked your emails. Once you find the initial block, analyze emails from the prior 24-48 hour period. Look for any unusual activity.

The #1 reason for Hotmail blacklisting your email is a security breach, either a compromised user account or web application that is sending spam.

Spammers use compromised accounts to flood hotmail.com and related addresses, e.g., outlook.com, with messages. If you have any email statistics tools, look for excessive logins by username or IP address. Usually, a user with a sudden spike in activity is the compromised accounts.

2. Check Sender Reputation

While Microsoft does not publish their filtering policies, they do reference Return Path in their documentation. Return Path provides various email delivery services, most notably a paid, whitelisting service for high volume senders. In addition to paid services, Return Path provides a free sender reputation lookup tool: SenderScore.org.

sender score

While the lookup above shows green for a score of 78, I’ve found that anything less than 85 starts impacting delivery.

3. Authenticate Your Email

Email sent to Outlook.com or Hotmail.com users should include Sender ID authentication. Microsoft currently checks:

  • SPF
  • DKIM

You can use a tool like mail-tester.com to verify that your email authentication is working.

I also recommend you check your PTR and DMARC records.  (If you have never heard of these DNS records, check out our DNS Records Every Email Marketer Must Know post.)

4. Outlook Postmaster Services

If you regularly send high volumes (100’s/day) of email to Outlook.com or Hotmail.com addresses, you should enroll in their postmaster services. Smart Network Data Services provides feedback on your IP ranges:
hotmail blacklist check services

If you want detailed reports, consider signing up for Outlook’s Junk Mail Reporting Program (JMRP). JMRP notifies you when an Outlook or Hotmail user flags your email as spam.

5. Hotmail Blacklist Removal Form

To remove your server’s IP from Hotmail’s blacklist, you need to complete their Hotmail Blacklist Removal Form.

Be sure to copy and paste the entire headers from a bounced email. The headers allow Microsoft to confirm the error messages and IP addresses.

A few hours after submitting the form, you receive a notification email:

Dear Jeffrey Huckaby

Please note that your ticket number is in the subject line of this mail.

192.168.1.1/32

Note: Errors are unlikely, however, if an error is indicated, please resubmit the specific IP or IP range.

Thank you,

Outlook.com Deliverability Support

Usually, within 24-48 hours, you should receive notice of their decision. Typically, you receive one of two replies:

  • Not qualified for mitigation
  • We have implemented mitigation
If you receive the not qualified response, reply to the email.  Ask for clarification as to why your IP did not qualify.  You will usually receive a response in 24-48 hours.   The response comes from a real tech who will work with you to resolve the issue.
If you IP qualifies for mitigation, you should see the Hotmail email block removed in 24 hours.

Useful Tools & References:

Hotmail Blacklist Bounces

Here is another bounce example:

host mx4.hotmail.com[65.55.37.72] said: 550 SC-001 Mail rejected by Windows Live Hotmail for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation problems. If you are not an email/network admin please contact your Email/Internet Service Provider for help. Email/network admins, please visit MSN Postmaster for email delivery information and support (in reply to MAIL FROM command)

The Hotmail rejection notice has essential information. In the example above, the 550 SC-001 is an important clue about why your server is blacklisted.

Hotmail Blacklist Bounce Codes

Hotmail publishes a detailed list of error codes:

SMTP Error Code

Explanation

421 RP-001The mail server IP connecting to Outlook.com server has exceeded the rate limit allowed. Reason for rate limitation is related to IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
421 RP-002The mail server IP connecting to Outlook.com server has exceeded the rate limit allowed on this connection. Reason for rate limitation is related to IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
421 RP-003The mail server IP connecting to Outlook.com server has exceeded the connection limit allowed. Reason for limitation is related to IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
550 SC-001Mail rejected by Outlook.com for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
550 SC-002Mail rejected by Outlook.com for policy reasons. The mail server IP connecting to Outlook.com has exhibited namespace mining behavior. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
550 SC-003Mail rejected by Outlook.com for policy reasons. Your IP address appears to be an open proxy/relay. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
550 SC-004Mail rejected by Outlook.com for policy reasons. A block has been placed against your IP address because we have received complaints concerning mail coming from that IP address. We recommend enrolling in our Junk Email Reporting Program (JMRP), a free program intended to help senders remove unwanted recipients from their email list. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
550 DY-001Mail rejected by Outlook.com for policy reasons. We generally do not accept email from dynamic IP’s as they are not typically used to deliver unauthenticated SMTP email to an Internet mail server. If you are not an email/network admin please contact your Email/Internet Service Provider for help. http://www.spamhaus.org maintains lists of dynamic and residential IP addresses.
550 DY-002Mail rejected by Outlook.com for policy reasons. The likely cause is a compromised or virus infected server/personal computer. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
550 OU-001Mail rejected by Outlook.com for policy reasons. If you are not an email/network admin please contact your Email/Internet Service Provider for help. For more information about this block and to request removal please go to: http://www.spamhaus.org.
550 OU-002Mail rejected by Outlook.com for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help.
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