[ferran_r]

I had same problem with deliverability of emails to Hotmail accounts a few years ago, they blocked AWS SNS IP email servers so sometimes were received but most of them directly sent to SPAM or never received. We complained Microsoft and their solution was to use one of their cloud email service or partner because the "black magic" of their AI filter. This is a shame

[cube00]

My favourite response from their so called "support" was to claim nothing was being blocked. They weren't going to let the full headers and error message from their outlook.com server convince them otherwise. Thankfully two days later it magically unblocked again. All the time enrolled in their "Smart Network Data Service" which did nothing. I probably just got an auto reply from the same bot Google uses to handle ban appeals.