Remove Your IP from the Hotmail/Outlook Blacklist

By on January 20th, 2020


Remove Your IP from the Hotmail/Outlook Blacklist

A suspicious or wrong email practice can lead o serious deliverability problems, such as spam placements, dropped and blocked messages, and more. These deliverability problems have a direct impact on your email performance and the sender’s reputation.

A mailbox provider often sends the IPs from which such emails are sent to their blacklist to protect their users from unwelcome emails. If the IP is under the blacklist, then the mailbox does not deliver the mails send from these IPs to the target recipients. Some of the mailbox providers with their blacklists to stop spammers are Outlook/Hotmail, Gmail, Yahoo, etc.


Why Hotmail/Outlook Blacklist your IP?

First, we need to investigate the reason why your IP was blacklisted. After investigation, fix the problem, and then Hotmail/Outlook removes your IP from the blacklist automatically. After fixing the issue, you can also request for IP removal from the blacklist. If you send multiple requests before fixing the problem, then your IP is submitted for additional screening. Some of the common reasons why Hotmail/Outlook blacklists and IP are:

1) If any Hotmail/Outlook users have registered any spam report.

2) If you have a misconfigured DNS settings and Bad IP/domain reputation.

3) If the bounce rate is high.

4) If there is a high volume of spam looking emails from an IP address.

5) If the IP forwarded any high-level spam message to Hotmail/Outlook users.

6) If your email volume is significantly changing.


Hotmail/Outlook Blacklist Check

First, make sure that your IP is blocked. You can check if the IP is blacklisted, by merely sending an email. If the Hotmail/Outlook has blacklisted your IP, then you receive a bounce notice similar to the one shown below.

<>: host[<mailbox_IP>] said: 550 5.7.1

Unfortunately, messages from [<your_IP_address>] 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 [] (in reply to MAIL FROM command)


No bounce notice means that there is a chance that your email is present in the spam folder, and Hotmail/Outlook does not blacklist it. The Microsoft email domains, such as,,, and, use the same blacklist. The following process to remove Hotmail/Outlook blacklist works for all of them. Make sure that you are getting a bounce notice before following the Hotmail blacklist removal process.


Hotmail/Outlook Blacklist Removal Process

1) Finding the Problem

First, you need to find why Hotmail is rejecting your emails by digging into the server logs. In the server logs, you can search for the following strings to find out why Hotmail blocks or blacklisted your IP/emails. Generally, any of these strings are available in the logs to show the bounce.

list (S3150)


Find the initial block to check when was the first time Hotmail/Outlook blocked your email. After finding the initial block, analyze the emails from the prior 24 to 48 hours period, and check for any unusual activity.

The spammers use some compromised accounts to flood the mailbox with messages. These compromised accounts can identify by using any email statistics tools. By using these tools, you can look for excessive logins. The compromised account is the user with a sudden spike in the activity.


2) Analyze Sender Reputation

Microsoft does not publish its filtering policies, but they do refer to the Return Path. The Return Path provides many paid services, such as email delivery service, whitelisting service for high volume senders, and more. One of the free services offered by Return Path is the sender reputation lookup tool. So, you can use this lookup tool to analyze your sender’s reputation. The lookup scores below 85 can start impacting the email delivery.


3) Authenticate Your Email

The users should include Sender ID authentication when sending an email to Microsoft email domains. Microsoft checks the SPF and DKIM as email authentication. You can use different tools like, to verify your email authentication. It is also recommended to check the PTR, DMARC, and DNS record to make sure that there is no problem with your IP.


4) Enroll in Outlook Postmaster Services

If you are regularly sending high volumes of emails to Hotmail/Outlook addresses, such as 100 emails per day, then it is recommended to add or enroll your IP in Outlook postmaster services. The Smart Network Data Service option in Outlook provides feedbacks about your IP range.

If you want to get notified, when anyone flags your email as spam in Outlook/Hotmail, then you can sign in to the Outlook’s Junk Mail Reporting Program (JMRP).


5) Hotmail Blacklist Removal Form

After investigating and fixing your email deliverability problems, you need to complete  Hotmail Blacklist Removal Form to remove your server’s IP from the blacklist. You need to copy and paste the entire header from the bounced email. This header helps Microsoft to confirm the error message and IP addresses.

After you submit the removal form, you receive a notification email with the ticket number. Within 24 to 48 hours, you get notified if your IP is qualified for mitigation or not.

If you have received the not qualified response, then you can reply to the email asking for clarification. A Microsoft tech responds you back with the reason within 24-48 hours. You can work with the tech to resolve the issue. If you have received the ‘we have implemented mitigation’ response, then the block is removed in 24hours.


Hotmail Blacklist Bounces

If you send an email and you receive a bounce notice, then your IP is blacklisted in Hotmail/Outlook. But from the bounce notice, only you get a clue about why your server is blacklisted. For example, in the following bounce notice, the 550 SC-001 is a bounce code. You can use this bounce code to identify why your server is blacklisted.

host[<IP_address>] 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)


Some of the Hotmail blacklist bounce error codes are:

SMTP Error Code Explanation
421 RP-001 The email server IP connected to Hotmail/Outlook has exceeded the allowed rate limit.
421 RP-002 The email server IP connected to Hotmail/Outlook has exceeded the connection rate limit.
421 RP-003 The email server IP connected to Hotmail/Outlook has exceeded the connection limit.
550 SC-001 Email rejected by Hotmail/Outlook due to policy reasons. The reason for this rejection can be the spam-like characteristics and IP/domain reputation.
550 SC-002 Email rejected as the email server IP connected to Outlook/Hotmail has exhibited namespace mining behavior.
550 SC-003 Email rejected due to policy reasons. This rejection occurred since your IP address appears to be an open proxy/relay.
550 SC-004 If the block against your IP is due to any complaint from other Hotmail/Outlook users, then your email gets rejected. You can use JMRP to remove unwanted recipients from your email list.
550 DY-001 If your IP is dynamic, then your email gets rejected due to policy reasons.
550 DY-002 If the email ends from a compromised or virus infected server/ computer, then the mail gets rejected as per policy.
550 OU-001 Email rejected by Outlook/Hotmail for policy reason.
550 OU-002 Email rejected by Outlook/Hotmail. This rejection may be related to the content with spam-like characteristics or domain/IP reputation.


If you need any further help, please do reach our support department.

16 Responses to “Remove Your IP from the Hotmail/Outlook Blacklist”

  1. Yoselin Abreu says:

    Error transferring to; SMTP Protocol Returned a Permanent Error 550 5.7.1 Unfortunately, messages from [] weren’t sent. Please contact your Internet service provider since part of their network is on ou

  2. Fernando Alarcón says:


    I need removed the IP of black list, please.

  3. saravanannani says:

    This server previously inbox .. after delivering mails we facing this bounce issues recently.

    Error: “550 5.7.1 Unfortunately, messages from [xx.xx.xx.0/24] weren’t sent. Please contact your Internet service provider since part of their network is on our block list (S3150)

    need to know how to solve this issues.

    applied Delist form — not getting mitigations.

    How to recover from bounce issues.

    • agentmiller says:

      please any news about this problem !

    • Alejandro says:

      The exact same thing happens to me and the worst thing is that a bot responds to you. And that my score in mail-tester is 10/10 and in mxtoolbox I have no problems. With CheckTLS the email encryption is working fine but … Outlook keeps blocking my emails and who knows why.

      • Hello Alejandro,

        Greetings from InterServer Support.

        Possibly the public IP from where you are connected would be blocked, We will certainly help you troubleshoot this issue. Please feel free to reach us at and we will review this issue and will update you through ticket.


        InterServer Support.

  4. NOC says:

    Dear concern,

    I need IP to be remove from the list. Please

  5. Mubeen says:

    Email Address Bounced (Notified HardBounce(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 (S3150). You can also refer your pr) by EmailServiceProvider at 2021-05-05 15:00:27(UTC) for Email: Company Information – Canadian Customer Debt Relief) while delivering Email Campaign “Company Information – Canadian Customer Debt Relief”.

    I need IP to be remove from the list.

    Senior Manager – LeadSquared Product Support

  6. jason says:

    BIBLIN: your link doesn’t work….. “unable to handle this request”, and its not the browser. Seriously MS needs to have a better system for getting your IP removed from their bolock list.. EASY to get on IMPOSSIBLE to get off! had one compromised account, i resolved issue in less than 2 hours, and here we are 4 days later and im still blocked form seindibg to hotmail, outlook, etc. COME ON people

    • The above links works. Kindly try via copying and pasting in the browser tab without clicking directly.

      Unfortunately, Microsoft will take several days to resolve these issues.

  7. jason says:

    remember people this site IS NOT Microsoft, Outlook, etc… its a web hosting company… only MS can unblock your IP….

  8. Siddharth Gupta says:

    Dear Team,

    Password is compromised and someone entering the services, changes made

    We have reset the password and changes all services password too

    This issue not happen again we changes made already so please unblock the IP for same. Please check below URL “”—–Please delist this IP asap

    Thanks & Regards

    Siddharth Gupta

  9. Pete Williams says:

    I believe block list (S3150) is returned when you send emails from a new IP address range for any domain other than a MS owned domain (hotmail/outlook/live).

    The new IP list is enforced even when you use proper SPF/DKIM on email server and Outlook.Protection will build your reputation over time. See for more information.
    The answer is patience as it took several days after following instructions to registering to JMRP an submitting “support request form”.
    Best wishes for safe sending.
    Pete Williams

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