The overwhelming majority of my email marketing copywriting includes a P.S. that restates the CTA.
In email messages that include several instances of the main CTA (typically five+ repetitions in a multi-paragraph message), the P.S. CTA is almost always the highest-performing CTA -- only second to the graphical button-based CTA.
(HubSpot's Email app does a great job of visualizing which links get the most clicks.)
I've used P.S. instances most often in email marketing that promotes webinars, as well as other thought leadership content offers.
How do you get a bigger CTA lift on your email marketing? Let me know in the comments below.