How Can I Use an Email Alias (Hide My Email) Created From Apple Pay?

When paying online with Apple Pay, my iPhone offered to create an email alias via Hide My Email for the vendor, which I did.

This list of email aliases is distinct from the ones you can create from Apple Mail, and won't appear there.

I'm now at a point where I need to email the vendor about something, but there's no option from Apple Mail to use this email address as a "Send As". Should I stop using Hide My Email for Apple Pay purchases if it can't function in both directions (both to receive email as well as reply to an email)?

EDIT: I apparently have the ability to reply to the email received from the vendor confirming my order, but I can't create a new email using the alias.