How Microsoft Junk Mail filter really works based in body content links?

I’m not here to discuss about DKIM, DMARC, SPF, or other of the hundreds of variables in the difficult path to get your email into the Inbox instead of Junk folder.

I’m here just about the links in the body content of the email, and I’ll tell you why.

I have been sending dozens of emails from a Google Apps mail account, to a hotmail.com account.

It was just TEXT, this text:

Hi there !!! Lorem ipsum dolor sit amet, consectetur adipiscing elit. Aenean sagittis imperdiet eros sit amet placerat. Aenean blandit efficitur eros non mattis. Integer vehicula nunc eget est vulputate, sit amet consequat ipsum feugiat. Aliquam massa odio, dignissim vel luctus in, aliquam sit amet est. Aliquam erat volutpat.   Phasellus egestas, dolor in tempor ullamcorper, tortor lectus auctor neque, vel suscipit diam tellus tempus tortor. Nam vulputate euismod ligula, ac tempor arcu tempus at. Donec ultricies velit sed justo mollis accumsan at nec nisi. Vestibulum a diam ac magna varius consectetur. Donec in justo vitae ex lacinia imperdiet. Nullam gravida urna leo. Etiam congue, dui a commodo feugiat, risus tellus tempor neque, eget vestibulum erat ex non augue.  If you want you can visit: https://xxxxxxxxx.xxxx  Donec pulvinar rutrum commodo. Cras porta facilisis bibendum. Pellentesque pretium est sem, ut varius diam suscipit quis. Aenean et eros auctor, rhoncus mi in, dignissim odio. Suspendisse suscipit enim lorem, quis interdum massa consectetur in. Integer suscipit eros sodales hendrerit tempor. Etiam finibus semper tellus, ac suscipit orci mollis eu. Pellentesque vehicula auctor ultrices. In hendrerit dolor quis lorem laoreet, vel convallis magna laoreet. Sed pulvinar non magna maximus dapibus.  Nullam semper lacus eget hendrerit dapibus. Morbi eget urna eleifend, consectetur elit ac, fermentum orci. Mauris et urna est. Mauris ac lacinia lectus. Vestibulum scelerisque tempor nibh ac eleifend. Nulla faucibus tellus blandit quam suscipit ultricies. Suspendisse finibus risus id lectus lobortis mattis.  Regards 

The only change was the ONLY link in all email content. Everything was exact the same. The content, the subject, the sender … I just changed that link.

What I saw is with some links, the email goes to Inbox folder With other links, it goes to the Junk folder.

Just that ! Just because of the domain name of the only link in the body content.

Why is that?

I try to figure out things like:

  • domain age
  • domain – ip and reverse
  • domain ip in ip’s blacklist
  • domain in domain’s blacklist
  • domain has https activated
  • and some other variables

but I can’t get any "rule" that satisfies why sometimes "that link" is "good" or not to Microsoft Junk Email Filter.

Does anyone know any clue in order to check the list of "good" domains and "bad" domains I have so we can all learn about this? 😉