Is there a way to preview an email before it is sent via email.send?

It’s hard to imagine a use case for this. Who would be doing the previewing within a script? Are they going to decide not to call email.send() if they don’t like what they see?

Pretty much the latter. The plan is to have a button on an SO that a user can send to a vendor using an email template.

I wonder if you can’t accomplish this with a workflow. Sounds like you’re not really using the email module, you’re just creating an email in the UI in an automated fashion so the user can type any changes before hitting a send button.