Version 0.5.1 is available upstream. Please consider updating!
It seems that version 0.5.1 is available upstream, while the latest version in the Gentoo tree is 0.5.0. You think this warning is false? Read more about it here.
This package provides some high-level datatypes for declaring MIME email messages, functions for automatically composing these into bytestrings, and the ability to send bytestrings via the sendmail executable. You can also use any other library you wish to send via different methods, eg directly to SMTP.