... and one / two more question(s):
Why should I use proxies or spintax?
Will I get a ban from anyone or why should that be needed?
Proxies is because if there a complaint (and there will be) then the proxy provider takes the complaint and not the host that your server is with.
As for spintax, I dont' use it, but you can. It just provides more uniqueness. I wind up just stamping out multiple campaigns for my needs. There isnt a wrong answer, just what works for you.
Sure, if you go ultra fast you will get what I call a high level blacklist, at which point your domains registrars legal department emails you and confiscates your domain.
What I call low level blacklist is when you get on lists that just lessen your delivery rate, spam haus is probably the worst.
If you get a hosting complaint to your website host, then you have to deal with your host or find a new one. If you dont' use proxies you could get a complaint to the server company that your sending the messages from.
So there are complaints all over the place, potentially, its not cut and dry nor is it exactly easy. So you must do your due diligence, and just figure out (probably thru experience) how to best mitigate the risks. That said Ive written at length about it in this thread, so just sit down and read all 25 pages of it (probably faster then finding out by experience).
All of those things aside, they are just pains in the rear, your real concern should be being legal. Specifically in the country your in, but also in any country that your going to message.
For example, I live in the USA and we have CAN SPAM. Im 100% CAN SPAM complaint.
I also message people in Europe and they have GDPR and ePrivacy. For the most part contact form marketing side steps GDPR because GDPR is about personal privacy so as long as you aren't using real peoples personal info in the message then you get a pass on GDPR. ePrivacy is a different matter, but its not so hard either.