[dataflow]

Keep in mind that with other communication mechanisms (e.g. email, SMS) we already send over a copy of the message and keep the original. I'm not saying it's "better" from a privacy perspective, just that it seems like the logical solution here, and I'm not sure how a court might conclude otherwise. The data is being hosted in Europe at that point. It's just that a copy needs to be sent to the recipient only when the message is initially sent (because how else do you communicate?!).

[stickfigure]

That's true for some kinds of PII data and not others. The social graph (who are your friends) is symmetrical. Shared-edit documents, dropbox-like file sharing, and wikis are often ownership-ambiguous.