i run my own mailserver and my emails don't land in spam folders... are you talking from first experience? if so, maybe i can help
I gave up (and don't need it anymore).
Did you setup proper email authentication (SPF, DKIM, and DMARC) and using "trusted" TLD? Was IP of your server is in known blacklist?
Not to mention that sometimes Email addresses are hard to write down by hand too, your own address is 21 characters long and that's a very simple one!
In this case, i would blame the owner of the email address for not choosing address that simple to remember.