You can use a VPS for web projects. For e-mail you'd want a dedicated server with a separate IP that is going to cost you €40/month. Yes it may take 1h to set up, but gaining reputation takes time - you definitely won't be able to reach all recipients within one hour of purchasing the server.
I sent emails from a VPS for years without issues. I stopped purely because Fastmail had better software and cheaper storage.
Could be Zoom messing up their logs, but could also be NAT from the provider.
A few years ago, me and my sister noticed we had the same IPv4 address, despite not living in the same household. We had different IPv6, though. It seems to be becoming more and more prevalent due to IPv4 exhaustion.
It’s incredibly irresponsible to take action against someone based on their IP address alone.
I always had the impression that using services like Mailchimp make that much less likely than doing it DIY on top of a more commodity transport like SES. I.e. they stay on top of and evolve with best practices over time so you don't have to.
Is that in any way accurate?