If you respect the hardest privacy laws everywhere then you are fine, if you want to have different code paths like
this guys in EU I can't spam them, I can't store private data without permissions but the other guys there I can do whatever I want but the other guys I can only do X but not Y,
I suggest to just respect the best/strongest privacy law, a good product is one that helps people do their work and gain more free time, I do not see how invading privacy will affect good products.
P.S. I am wondering what laws made it so today most emails have an Unsubscribe link at the bottom, this is such a good thing, I would hate some companies not adding it for the countries where it is not mandatory.