Devel and admin manual: add pop3_connector chapter.
Admin manual (it): update mail chapter
Admin manual (en/it): update mail chapter
Developer manual: add mail chapters
Developer manual: fix syntax
Update mail.rst

Minor adjustments
Update mail.rst

Modifiche minori
Update backup.rst

A little clarification on configuration backup and data backup
Update backup.rst

A little clarification on configuration backup and data backup
Touch debug file to unlock index_dev.php
Devel manual: update dhcp chapter
Admin manual: update firewall chapter
mail.rst: applied word wrap (fill-paragraph) to rst source.
mail.rst: refactored and reformatted.
mail.rst: added references to components web sites.
mail.rst: Log section.
mail.rst: fixed Spam section.
mail.rst: fixed Mail Queue section.
mail.rst: fixed HELO section.
mail.rst: Refactored Mailboxes. Queue management section merged with Messages.