[NEW]mail/p5-Mail-Message

Hi, ports@:

Here is a patch to create new port mail/p5-Mail-Message.
It build and run well on amd64-current system, pass all tests.
It is required by the update of p5-Mail-Box.

Before commit this patch, the patch to update misc/p5-User-Identity
should be committed.

Cheers !
wen