My assumption is that they at least have an intern read them, but only act on reports likely to lead to major cases, for some value of "major" that includes cases where terrorism, large sums of money, or Important People are involved, or more generally cases that could lead to seriously good/bad PR if pursued/ignored.
De minimis non curat FBI.
They may also flag certain cases to be passed to other relevant authorities like FinCEN, the Secret Service, the Postal Inspection Service, various military investigative services, or even the intelligence community (assuming NSA doesn't already intercept the mailbox which would be a very reasonable thing to do).
De minimis non curat FBI.
They may also flag certain cases to be passed to other relevant authorities like FinCEN, the Secret Service, the Postal Inspection Service, various military investigative services, or even the intelligence community (assuming NSA doesn't already intercept the mailbox which would be a very reasonable thing to do).