Email::Abstract provides module writers with the ability to write
representation-independent mail handling code. For instance, in the cases of
Mail::Thread or Mail::ListDetector, a key part of the code involves reading the
headers from a mail object. Where previously one would either have to specify
the mail class required, or to build a new object from scratch, Email::Abstract
can be used to perform certain simple operations on an object regardless of its
underlying representation.

Email::Abstract currently supports Mail::Internet, MIME::Entity, Mail::Message,
Email::Simple and Email::MIME. Other representations are encouraged to create
their own Email::Abstract::* class by copying Email::Abstract::EmailSimple. All
modules installed under the Email::Abstract hierarchy will be automatically
picked up and used.

For this reason, the tedious process of looking for a valid date has been
encapsulated in this software. Further, the process of creating RFC compliant
date strings is also found in this software.