This matches my experience completely. My current and longest single job is as a US Federal contractor. You might get a political word or two over lunch off bas

This matches my experience completely. My current and longest single job is as a US Federal contractor. You might get a political word or two over lunch off base around here, although the civil servants tend to be more tight lipped than us contractors for the aforementioned reasons. You would never in a million years see any kind of political discussion occurring via email, no matter if it was government or contractor email or people. As far as I know, it's not even an official policy (beyond standard government "for official use only" policies), there's just not sane reason to ever do it.