I think FedEx is the toughest on this, and here is what we require:
Eligibility for rapid visa issuance, issued by offices in the United States to fly to any FedEx destination.
Ability to obtain clearance from United States Postal Service for handling or access to U.S. mail, which includes FBI fingerprint check, and candidate must have resided in the United States for the last five consecutive years (except for U.S. military assignments)
Eligibility for issuance of US Security Clearance