I've been in your position so I understand your frustration, but what you're describing is not evidence of a monopoly.
A monopoly situation would have some kind of limits enforced, correct?
I have dealt with spam issues with Gmail and solved them all. I send HTML formatted email to many Gmail accounts. I suspect you have not setup SPF, DKIM or are blacklisted on spam lists. Or if you've done all this, possibly the formats for your emails is suspect. Either way, it's solvable. At the very least, your clients could white list your domain.
Edit: I am not saying it's pleasant, but it's hardly monopolistic behavior...
No. A monopoly simply means market domination. It can arise naturally, as has been the case for Google in search in the past.
Microsoft had a monopoly on operating systems without "enforced limits".
The specific legal tests often require e.g. "over 80% of relevant market" by some measures - and I'm not sure Google mail qualifies as a monopoly under this definition.
p.s. having a monopoly isn't even illegal - abusing a monopoly position is. It feels to me that Google is, in many ways, abusing its dominant, perhaps monopoly, position in mail handling.
> I suspect you have not setup SPF, DKIM or are blacklisted on spam lists. Or if you've done all this, possibly the formats for your emails is suspect.
In what sense is this "work[ing] just fine?" "Sorry, we threw away your mail for some random reason, and we won't tell you about it" seems like poor service.
I did testing and found it was not random. Also, maybe my experience running SpamAssassin in the past helped me. Look up how SpamAssassin filters emails and it may help you with your problem.
Feels as monopolish as any other monopoly i’ve seen in technology.