gmailed marked email as spam and outlook blocked email

Hello, I setup a mail server using a Ubuntu CyberPanel droplet, everything is properly configured. Test results are 10/10, link here:

The following message was received from outlook:

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 (S3140). You can also refer your provider to [] (in reply to MAIL FROM command)

Please help

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Bobby Iliev
Site Moderator
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July 17, 2022


What I would usually suggest in such cases, is to send an email to the following website which will generate a nice report highlighting the reasons that might be causing the problem that you are seeing:

On another note, what I could also suggest is going through the following tutorial on why you might not want to run your own email server:

Hope that helps!

- Bobby.