Can I change the email domain my emails are sent from?

Yes, on the Pro plan and above. Go to Settings > Site Settings and scroll to Custom Email Domain. Connecting it works the same way as a custom site domain — you'll need access to your domain's DNS records, and you'll follow the prompted instructions to add the required records and verify the connection. Once connected, emails sent from the platform will use your own email address/domain instead of the default.

This isn't available on the Free plan.