You can self host email. There are plenty of how-tos, prepackaged packages, even books:
https://mwl.io/nonfiction/tools#ryoms
I'm writing my own how-to which includes finding suitable Internet providers and includes setting up smarthosting in case you can't get a good address for yourself.
You don't. Google doesn't have humans that non-paying customers can reach.
As I wrote, either you work on improving your reputation (set up all the acronyms, send lots of test messages, tell everyone you know that uses Google for mail to look in their filtered mail and tell Gmail that your mail is not junk, keep sending, et cetera), or you smarthost through a reputable service.
You can self host email but less (maybe much less) than 50% of what you send will actually be received by the recipient, particularly for recipients at major providers like gmail, etc.