Hotmail rejecting all emails using Mailgun or SparkPost


Solution 1

Seems like there is some problem with the IpAddress that Mailgun assigns you.

All I had to do was to go into the domain i setup at Mailgun there was an IP address assigned to my domain. I removed it. It assigned me a new one and done.

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Solution 2

I recently encountered this issue as well - I highly recommend that you reach out to the Mailgun support team and notify them of the issue. They recognized that the IP that I was on was associated with a user who had been sending a lot of spam and they hooked us up with a "clean" IP. I'd guess that if you delete your IP and they automatically assign you a new one, that can work but might not be a guaranteed fix if the new IP is also blacklisted - just let them know, they'll help you out.


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Syed Abdur Rehman Kazmi
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Syed Abdur Rehman Kazmi

Full Stack Web developer,who loves to bring brilliant ideas to life,I love challenges and I try to find them everywhere,learning is my habit and I'm always hungry for it.I build teams,brainstorm on ideas and execute them, I like doing things in an artsy way.

Updated on June 04, 2022


  • Syed Abdur Rehman Kazmi
    Syed Abdur Rehman Kazmi over 1 year

    I have been trying to send mail using Laravel. I have been successful in integrating Mailgun/SparkPost in my application. It is sending mail to every other domain except for Hotmail/Outlook/MSN/Live. Somehow they are saying that the IP I am trying to send mail from is on their blocked list.

    This is the error message i keep on getting:

    Failed: [email protected][email protected] 'User Verification Reminder Mail' Server response: 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). You can also refer your provider to []

    When I tried to reach out to Hotmail's support and explained my issue to them, this is the reply I got from them.

    Dear Abdur Rehman Kazmi

    We have completed reviewing the IP(s) you submitted. The following table contains the results of our investigation.

    Not qualified for mitigation Our investigation has determined that the above IP(s) do not qualify for mitigation. These IP(s) have previously received mitigations from deliverability support, and have failed to maintain patterns within our guidelines, so they are ineligible for additional mitigation at this time.

    Please ensure your emails comply with the policies, practices and guidelines found here:

    To have Deliverability Support investigate further, please reply to this email with a detailed description of the problem you are having, including specific error messages, and an agent will contact you.

    Regardless of the deliverability status, recommends that all senders join two free programs that provide visibility into the traffic on your sending IP(s), the sending IP reputation with and the user complaint rates.

    Junk Email Reporting program (JMRP) When an user marks an email as "junk", senders enrolled in this program get a copy of the mail forwarded to the email address of their choice. It allows senders to see which mails are being marked as junk and to identify mail traffic you did not intend to send. To join, please visit

    Smart Network Data Services program (SNDS). This program allows you to monitor the ‘health’ and reputation of your registered IPs by providing data about traffic such as mail volume and complaint rates seen originating from your IPs. To register, please visit

    There is no silver bullet to maintaining or improving good IP reputation, but these programs help you proactively manage your email eco-system to help better ensure deliverability to users.

    I am using Laravel 5.4 and i am able to send mails to every other network i.e gmail/yahoo

    • sam
      sam over 5 years
      The cheaper the host, the more likely they are to have been used for spam and so the more likely they are to have blocked IP addresses. You can find that the IP address in question is on many blocklists used by various providers. You need to reach out to your providers and if they can't resolve it by removing the IP from rotation then you'll need to switch to another provider.
    • Syed Abdur Rehman Kazmi
      Syed Abdur Rehman Kazmi over 5 years
      i am using aws for hosting. it is a free tier account currently
    • inquilabee
      inquilabee over 5 years
      Was your problem solved? How did you solve it?
    • Syed Abdur Rehman Kazmi
      Syed Abdur Rehman Kazmi over 5 years
      Yes. i am answering it here
    • Admin
      Admin almost 4 years
      I'm voting to close this question as off-topic because this doesn't seem to be directly related to programming.
  • Thomas Neuteboom
    Thomas Neuteboom over 5 years
    Thanks for sharing!
  • user1040259
    user1040259 over 5 years
    this does not work, mailgun will not allow one to remove a shared IP and have it automatically reassigned.
  • Trixz
    Trixz about 5 years
    But you get a new shared ip from mailgun, and hopefully it's not blocked
  • brother Filip
    brother Filip about 5 years
    It worked for me at first. After a few minutes MG changed the IP to one which is blocked. I tried to remove it and got another which was also blocked. I tried it multiple times but it seems I am stuck with these two IPs:,
  • Muz
    Muz over 4 years
    This worked for me. I think they no longer let you get a new IP by simply removing the one they assign you.
  • BBlake
    BBlake over 4 years
    Anyone have another solution for this? No matter how many times I remove the IP address, MailGun reassigns the exact same blocked shared address. I've also tried SendGrid, Mandrill and Dyn. All blocked by IP address for Microsoft email domains.
  • skwidbreth
    skwidbreth over 4 years
    @BBlake contact Mailgun directly and explain the problem, they'll help you. Worked for me.
  • Prasad Gayan
    Prasad Gayan about 4 years
    I have the same issue in sendgrid, and they also said to change the plan and get a dedicated IP which is higher cost. Because shared ips most of the time blocked by Hotmail.
  • John Chandler
    John Chandler almost 4 years
    I have the same problem. The mailgun dedicated ip is $59 per month which is prohibitive. I fail to see why it has to be so expensive. We run a woocommerce site and some of our customers use Hotmail and they never get any email from the site. It should be possible to fix this for a reasonable cost. We only send a few thousand emails per month so we don't need the Cadillac solution. But we need a solution.