Hi @DaveGoff2,
There currently isn’t a default aggregated view of email clients used. I can’t find any ways to create a custom report to visualize this information either. At this stage, you’d have to look at individual emails under Menu > Marketing > Email and scroll down to “Opens by email client”:
Once you’ve checked 4-5 emails, you should have a pretty good idea of the clients used by your recipients.
Hope this helps!