Hotmail emails not working

Strand Games is having ongoing problems with, Microsoft are rejecting all emails to this domain from

This will be a problem if you're trying to register on the forum with a hotmail email address.

Story so far;

Emails are rejected with the following;

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 (AS3140). You can also refer your provider to
[] (in reply to MAIL
FROM command)

Apparently Microsoft operate their own system whereby they don't like anyone running their own independent mail server. See here.

Are you sending email from new IPs?
IPs not previously used to send email typically don't have any reputation built up in our systems. As a result, emails from new IPs are more likely to experience deliverability issues. Once the IP has built a reputation for not sending spam, will typically allow for a better email delivery experience.

Additionally our IP address is not on any blacklist, check.

We have contacted Microsoft here but as yet there is no resolution.


  • We've tried requesting an unblock here but no news yet....

  • edited March 2018

    For anyone interested in the problem of detecting spam, this was solved way back in 1992 by Cynthia Dwork and Moni Naor and Eli Ponyatovski in their 1992 paper "Pricing via Processing or Combatting Junk Mail" via a proof of work system called hashcash.

    You can read about the hashcash algorithm, but it elegantly solves the problem of sending bulk spam email.

    Perhaps large companies wouldn't want to waste the CPU on mass mailings, but the few who need to do that could easily be white-listed.

  • The reply;

    Dear jkj yuio

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

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

    Thank you, Deliverability Support

    Please do not reply to this message as it is from an unattended mailbox. Any replies to this email will not be responded to or forwarded. This service is used for outgoing emails only and cannot respond to inquiries.

  • Further update from MS:

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

    Conditionally mitigated
    Our investigation has determined that the above IP(s) qualify for conditional mitigation. These IP(s) have been unblocked, but may be subject to low daily email limits until they have established a good reputation.

    Please note that mitigating this issue does not guarantee that your email will be delivered to a user’s inbox.

    Ongoing complaints from users will result in removal of the mitigation.

    Mitigation may take 24 - 48 hours to replicate completely throughout our system.

    So it's possible that it might now actually work!

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