We have person profiles for internal testing, but I don't want internal communication synced to PipelineDeals. How do I prevent that?

If you have internal profiles for testing and you use Gmail, you will have your email record synced up to that profile, however, there is an easy workaround. You can add "+test" to the end of the email address - for example: example+test@example.com - and the original address will still receive emails that you send to that address for testing (in the example above, emails sent to example+test@example.com would be received by example@example.com) but the system won't recognize it as the same email for the Email sync, so your internal communication wouldn't be synced up to your system. This works because the receiving mail server disregards anything after a plus sign - you could put anything you want in there and the original address will still receive it.