Mail::Box

Inheritance is the most important feature to get everything to work: you create general (base or super) objects, and then you specialise (derive or subclass) them.

When we create a MIME::Entity object, we have a basic message (Mail::Internet), with extra functionally primarily about understanding the message's body.

The UNIVERSAL package is the general super-class, but only defines three methods: isa(), can(), and VERSION().