,, blacklisting... a pleasant experience

Posted: 2017-07-10 16:59:01 by Alasdair Keyes

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I've recently migrated my server to

And upon sending an email to Hotmail, I received the dreaded bounceback...

SMTP error from remote mail server after MAIL FROM:<someemailaddress> SIZE=4705: host []: 550 SC-001 (SNT004-MC9F10) Unfortunately, messages from weren't sent. Please contact your Internet service provider since part of their network is on our block list. You can also refer your provider to

The URL links to the following description of code SC-001.

Mail rejected by for policy reasons. Reasons for rejection may be related to content with spam-like characteristics or IP/domain reputation. If you are not an email/network admin please contact your Email/Internet Service Provider for help.

My IP is not on any well known block lists such as or so I had no quick and easy way of delisting.

I was hit with a sense of sudden dread and the horrible sinking feeling that you only get when you realise you have to speak to a support team at a large multi-national IT company.

You know what's coming.... hours of arguing that it's not a server misconfiguration, my DNS/SPF/DKIM/MX setup is all actually valid and correct. Waiting days for a reply to your well reasoned email only to receive a canned response that doesn't address anything close to your complaint. yadda, yadda, yadda.

Or so I thought... I found the following "Sender information form" at which I filled out and within an hour I had received a couple of emails back from Microsoft saying that they had conditionally mitigated the the restriction on my IPs and that emails will be allowed through at a decreased rate-limit until such time as reputation has been improved.

I left a couple of hours and I was able to send to Hotmail with no bouncebacks!

OK... so Microsoft can really try harder with their URLs and user/search engine friendliness but I was incredibly impressed with their response on this. It used to be that Hotmail would often blackhole your emails and you had no recourse, but they really seem to be on the ball with this and I'm most impressed.

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© Alasdair Keyes

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