Yogstation 13 - Modules - Types

code/game/objects/items/mail.dm

/obj/item/mailMail is tamper-evident and unresealable, postmarked by CentCom for an individual recepient.
/obj/structure/closet/crate/mailCrate for mail from CentCom.
/obj/structure/closet/crate/mail/fullCrate for mail that automatically generates a lot of mail. Usually only normal mail, but on lowpop it may end up just being junk.
/obj/item/storage/bag/mailMailbag.