I doubt that it would be possible to approve all the invoices in that email, because the email could be 2 weeks old in someone's inbox and when they come back from vacation, the list of invoices that they need to approve will no longer be what was on that email.
But there can be a button in the email to have a 2 step approval. The link in the mail would open up Quick Base and show the list of invoices to approve.
That report could have a button to approve all invoices. This can probably be done with native setup (no javascript), but it would be beyond the scope of this forum to attempt to describe the detailed steps.
Contact me via the information on my website QuickBaseCoach.com if you want to pursue this off line.