Composing that "letter" was a federal crime.
I'd ask, what letter, but never mind.
She wasn't even really accused of sending "classified" (not really) info, but just of receiving it and not realizing that when you get an email about a NYT story about a program the government denies, they consider that "classified" once it's in a government email.
That's just some crazy shit right there. The FBI realized this, realized that any prosecutor arguing that in front of a DC jury would look like a bigger fool than Ken Starr.