So, if I would be in the USA and I receive mail from someone who is criminal then they need to be in my mailbox to see what the criminal wrote?
And if any number of people (spammers) send mails to me with 'criminal content' then MY mail (the recipient) is under investigation?
Then they invade my privacy and not that of the supposed criminal?
Or am I seeing things wrong here?

Then what can a traveller do to fight this?

And if some site like Wikileaks publishes some secret mails then wikileaks is criminal and not the criminals who hide behind a political wall?

Twisted....