First off, you don’t really have control over your external IP reputation, unless you have your own IP space, which most people don’t.
You’re at the mercy of your colo/hosting, really. You get whatever IP they give you, baggage included. I think the reputation is also subnet-based, not IP based, so your potential to be included in someone else’s blast radius is increased.
Also, even with a clean IP, the steps you outlined are not sufficient to send significant numbers of non-spam messages and not get spamboxed. Gmail seems to be mostly okay with erring on the side of false positives.
Source: been running my own email servers for 25 years
(btw my mails also seem to get through and i haven't even set up DKIM)
Plenty of people report that there is a minimum amount of email you have to send so that you can contact gmail and ask them to unlock you. They, of course have a set of rules you have to follow.
But you won't get them to receive your email if you just send some 3 messages a week.
- ensure your external IP reputation is good. Check blacklists.
- configure correct dns/reverse dns (PTR) records.
- setup SPF (maybe DKIM with DMARC but I'm not using these)
- do not spam.
Thats it.