This is an extremely important point, and I find it weird to see so few people mentioning it. I run my own mail server and have been for years. My e-mails use

This is an extremely important point, and I find it weird to see so few people mentioning it. I run my own mail server and have been for years. My e-mails use SPF, DKIM, DMARC, I have a reverse DNS record set up, a score of 100/100 on mail-tester.com... yet Microsoft refuses to accept my emails. They are sent to the spam folder of my recipients. I tried contacting their support about it, I'll let you guess how well it went. A man from a warm country told me to join some sort of Microsoft partner program, for which I would have to pay. This is a disgrace. E-mail is behind closed gates now, because of bullies such as Microsoft.