Gmail is hit or miss, even when dkim/spf/dmarc are setup correctly. It may work 70% of the time, but it becomes a constant guessing game if you inboxed or went to spam. If you're using DO/Vultr/Linode, there may be issues with noisy neighbor IPs, but it still sucks that you may get penalized for no fault of your own. It seems like there is no incentive for Gmail to play friendly with small mail servers.
This is great! Thank you!. I scored 2.7 out of 10. I'm using NameCheap's Private Email service. What a waste!
Age may be a factor. I ran email for my domain on my own server for a long time too and generally had no delivery issues.
When I got another domain a few years ago and ran it on the same server it had a lot of delivery issues.
Probably. Although I switched both IP and domain a couple of years ago (not at the same time) without noticeable issues.
No email server in the world can deliver 100% (not even Gmail). Here you are claiming to have done that for 20 years straight. Well, it's not true. In fact, I'll venture as far as to guess that you've never even measured your deliverability.
That’s hyperbole. I‘ve been running my personal mail server on a VPS for the past 20 years and never had any delivery issues. It may depend on the hosting provider you use, and nowadays you probably need to have DKIM etc., but there are a lot of people running their own mail server without issues.