Even paid email you can be identified as a spammer. I use Namecheap's private email for my side project. I do zero marketing/automated emails.

All of a sudden my hand written emails to clients were going to spam. Namecheap verified my spf/dmarc/etc was all setup correctly and told me there was nothing they can do.

I don't communicate often and am just using my personal email address for now, but I'm looking to switch providers