Are there any tips/guidelines on whether or not our customers should include a QR code in their creative?

I don’t recommend QR codes within email because if they open the email on their phone, what are they going to scan it with? Email allows you to click directly on images to drive you to the link that the QR code may be associated with, having a QR code doesn’t add much value to email. QR is great for printed ads and tv/streaming as it allows you to simply scan.