That’s because PHP mail is blocked on our hosting. And even if it wasn’t, you currently only configured your domain for Porkbun’s email hosting, so email sent from us would likely be considered fake and flagged as spam or discarded entirely.
You can edit the email address directly through the database to bypass the email verification issue for now. But if you want to be able to send email from your website, you may want to consider installing an SMTP plugin like WP Mail SMTP and hooking a mail account into it. If PorkBun provides an email account with SMTP, you can use that to send email from your site as well.