I do, a bit differently from what’s been mentioned here so far:
I actually host my server at home, running mailcow as my email-server-software of choice, and incoming emails do get delivered directly to my ISP-assigned IP via dynamically updated DNS records.
However: Outgoing email is delivered via an SMTP relay service, specifically Mailgun (I like them because for normal everyday email volume it’s free), because even when I was hosting the email server in a datacenter, it was impossible to not encounter deliverability issues.