>ip reputation

Get this. I owened a /23 for 7 years (still own it today) and kept the mail server ip on a /27 just for the mail server on a /24 that was not used for anything production (firewalled and maybe 3 ip's responded on port 443). My mails were banned for bad reputation. The provider which hosted my /23 was well known for responding to abuse, even falsely flagging my account as abusive in the early days for simply _sending_ valid smtp mails.

IP reputation turned out to mean, if they never saw your IP, you were in the banned bucket. How do you even fight against that

No, that's because your relay overwrites part of the header which makes dkim strict break. Change to relaxed or don't modify the header on your relay.

Outlook business will accept your mail, Outlook private may filter, but the rates fluctuate so heavy i suspect its rules based on user behaiviour/interests. I dono, cant have both spamfree inbox and 0 false positives.

I think i found a loophole for the google and outlook ones... I have had my domains on both providers, and then left to my own (but left a couple of google and ms txt records by mistake) and never had any issues delivering to both providers. Thinking of doing the same thing again honestly, but looking at good providers at the moment.

I hate the fact that your comment got flagged / greyed out / whatever even though it's perfectly correct. I'm one of those people who had configured everything perfectly. Score of 100 on mail-tester, SPF, DKIM, DMARC, you name it. Examining the headers in an e-mail sent to gmail: pass, pass, pass. Everything green.

Microsoft however? Denied, 100% of the time. Spam folder, or even plain rejected. Why? No idea, they won't say. They redirect you to their shitty partner that you can PAY in order to HOPE you get approved.

I don't know why our experiences are considered "anecdotes", and not the other way round. What's the incentive for big players to accept e-mail from home servers or small dedicated servers? "Sure it could be Standard Nerd from HN running their own stuff for street cred points, or it could be one of the bazillion spam factories sending fake UPS scams. In doubt, let's reject."