Here it is, the 2025 Spam Resource MAGY (Microsoft, Apple, Google, Yahoo) Bulk Sender Compliance Guide. This contains almost everything you ...| www.spamresource.com
So you have setup your own mailserver with Dovecot and Postfix and it's working fine (DKIM, SPF etc), except for sending mails to Hotmail and Gmail. The problem: Sending mail to Hotmail/Gmail Guess what, you are not the exception, many people with self small hosted mailservers complain about Gmail| Maikel.pro Blog