The Secret Service said the letter to Obama was intercepted by a White House mail screening facility, and it was turned over to the FBI's Joint Terrorism Task Force for testing and investigation.
The task force said the decision should be based on individual considerations and said overscreening caused stress, unnecessary testing and other negatives outcomes.
Executives have cited the difficulty of that task as a key reason for the long lead-up to the new pay system and have been testing and debugging the system.