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OstinatoFreak 16 Reputation points

8 years ago, a hacker used my email address (a custom domain name) to send spam. I caught it in 20 minutes and stopped it, but it was enough time to damage my domain reputation. I spent the next year cleaning it up. I was successful, and to this day I can email everyone with no problem. EXCEPT FREAKING HOTMAIL. With Hotmail, it's hit and miss. Most days I can email people with Hotmail accounts. But other days, I get the error below. Keep in mind I just emailed this person like 30 minutes before this, and the email I sent to this person was a reply to an email THEY SENT ME. I had not sent any large numbers of emails today; just a couple here and there, and none to other Hotmail people.

Is it possible for me to be put in touch with someone who has the power to affect Hotmail's spam filters?

E-mail error message (my message was sent on Mon 3/7/2022 10:28 PM, received this error also at 10:28PM):

This is the mail system at host

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own text from the attached returned message.

                   The mail system

<********>: host[] said: 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 provider to
    [] (in reply to MAIL
    FROM command)
Outlook Management
Outlook Management
Outlook: A family of Microsoft email and calendar products.Management: The act or process of organizing, handling, directing or controlling something.
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  1. ChristyZhang-MSFT 21,261 Reputation points Microsoft Vendor

    Hi @OstinatoFreak ,

    Welcome to our forum!

    Does this issue occur when you sent specific recipients? If so, what are their similarities?

    According to the error you provided, have you tried the recommendation that you have directly in the email: 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)?

    If so, what was the answer of your provider? If not, please contact your provider first to solve this problem.

    In addition, based on my research, I found in some thread some users mentioned that it's useful to use delist portal to remove yourself from the blocked senders list. Maybe this is also useful for you. It is recommended that you try this operation and check whether it works.

    Hope the above help!

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