Subtitle: The new bussiness model of freemail hosters.
How can you make money from free e-mail?
Easy: Charge Admins for getting their mails delivered.
If you are not interested in my story, just skip to the most important part at the end.
Months ago Microsoft decided to classify mail from my server as spam and did not deliver it to the inbox of their freemail services like live.com, outlook.com, hotmail.com, … This was even before I migrated to my new system with IPv6 (OK Microsoft doesn’t care) and another V4 IP. I even tried with both machines and the same thing happend.
A few weeks ago now – suddenly – Microsofts’ servers started to bounc all my mails with the message: “Please contact your Internet service provider since part of their network is on our block list.” Of course I immediately checked public blacklisting services to see if my IP is listed somewhere – but nothing. All the other big providers also worked fine.
I double-checked their guidelines such as that reverse DNS and SPF must be configured properly, but everything was fine.
So I finally decided to open a ticket to ask to remove me from the blacklist. They in fact did this “for conditional mitigation” as they wrote and now I’m back to normal: Mails are delivered to the spam folder.