psyop-military actions designed to influence the perceptions and attitudes of individuals, groups, and foreign governments.
Choose certified mail when you need proof of delivery and time is of the essence. Registered mail is the Postal Service's most secure form of mail delivery, involving an unbroken chain of custody. Registered mail is protected in sealed containers, safes and cages, and held under lock and key.
1st Class and Certified Mail is delivered at the same time rate. 1st Class Mail is delivered to an address. Certified Mail is personally delivered, and requires a date/time signature of receipt. It costs more for this verification. You send 1st Class mail to those when it's good enough that it gets there.