alt Hacker NewsNot an expert, but I suppose that you can safely receive email using a self-hosted SMTP server. Sending it without being blacklisted / greylisted is trickier. If you don't want to muck with obtaining an IPv4 with a good karma, there are options to send via large providers, such as GMail (IIRC free), or AWS SES, or things like Sendgrid or Brevo. The latter may be effectively free if you send only a handful of emails per day.
I found when I tried out using SES, Sendgrid, Brevo, etc to send emails for my self-hosted exim instance, that my deliverability actually went down compared to sending the mail directly. I believe it was because for the free/low cost tiers they dump you onto IP addresses where they're also playing wack-a-mole with spammers. SMTP2GO was the only one I found that had decent deliverability at a free/low cost for low volumes. Still, I only use it for my personal email. For my business, I host our mail on Fastmail.