I'd say the advantage of 'Locke Mail' is that it gives the right associations even to people who haven't heard of John Locke. Locked Mail. Mail protected by a (cryptographic) lock.

>Without searching I have no idea what that is supposed to mean. I guess it is something related to free speech in the USA?

He was a British philosopher from the 1600s, an important Enlightenment thinker.

He might be fitting in relation to US history considering that while he spoke of equality and freedom, he was a major investor in the slave trade (he also was involved in trying to introduce a feudal aristocracy in Carolina).

He was very progressive for his time, and so he's one of the "icons" of classical liberalism, but he died in 1704, and we've moved on a tad from then.