Email is all about reputation: it can take a lot of effort to build trust, but just one bad move and it's all gone.
From the comments here I get the impression that this means, “don't do anything Google's machine learning environment cannot interpret”, which has the added drawback of not ever knowing if you are doing something it considers unexpected.
Is it though? That may well be true for small individuals, but the Spam I get these days comes via the large mail providers, Amazon SES, sendgrid etc, and nobody in their right mind is going to block them. "Too big to block" is a thing now, "too big to have to care about abuse reports" is too.
If that doesn't work out, is their reputation not good enough? Is the receiving server too strict? Are those blocks occurring on major providers or for individual servers where an annoyed person might just blacklist an IP if they get spam from them more than once?
We got blocked once because we got a single spam click: the ISP said they have a zero tolerance policy. We had years of sending hundreds of email per week without a spam click.
In my experience, the email blacklists and filters are somewhat forgiving. I accidentally configured my email server as an open relay (didn't know what that was at the time), and for a brief period was sending a not insignificant percentage of spam worldwide.
Once I discovered my mistake and corrected the issue, I was able to submit domain removal requests to the various blacklists, or just wait for my domain to fall off the radar. I expected it to be worse, and was pleasantly surprised to find that this kind of "forgiveness" is really an industry standard.
But then, that was just one bad move. I'm not so sure about two bad moves, and I'd rather not find out.