Confirmo que ainda me acontece de vez em quando, sim

I self-host my own mail server. I don't send many emails, but they seem to be arriving correctly whenever I do at the moment, but it wasn't always like this. I've properly setup SPF, DKIM and DMARC, which helps a lot, but my IP address was blacklisted on some servers from a previous owner I guess. I have a VPS from OVH. I had to manually fill out some forms to get Microsoft Outlook to accept emails from my server. Despite that, it has been working flawlessly. I have my own domain since 2017, and I'd say the age of the domain is also important.