Last night we discovered a mistake in a new custom email template.
Our developer fixed the mistake, today.
Meanwhile, an approved email was using the template with the mistake. Would our developer's fix automatically update the approved email if it had not been sent yet?
If not, does the approved email have to be scrapped and rebuilt completely, or could we just unapprove, then re-approve it to automatically update with the new template? (It was a relatively minor change in the template, but grossly affected our campaign.)
Has to be unapproved first! Then re-approved.
You don't have to rebuild it, unless your developer made another template. But that doesn't sound like the case.
A quick note here that email template re-approval only corrects things if it is part of the core template itself. If, say, you're updating a module, you must bring the newer version of the module into the email and edit it appropriately.