... the email is going to go through someplace - we don't have a choice about that - and one of the clearest points to come out of everything we've learned is that your ISP is probably the weakest link in the chain for all of this stuff.
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So yes, having your files on a server would make them less easily seen by the government. But then you're more susceptible to the other drawbacks of local storage.
I was mostly referring to document storage rather than email, since secure end-to-end email communication is a non-existent thing for most small companies.
I don't know how such things are currently viewed in the lawyering business but having a duty to maintain privacy of confidential documents rubs up against the reality of trusting an external entity with those same documents.