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.
mail.rst: Fixed Email addresses.
mail.rst: missing features

- Enable Move to "junkmail" folder" before Bayes training
- Describe "Add a prefix to spam messages subject"
mail.rst: fixed event name
migration.rst: expanded Email section

Prefixed all cross-references with "email_"
mail.rst: added sieve

- Fixed authentication protocols and ports
mail.rst: added antivirus checks note
samba.rst: added cross-references and footnotes.
mail.rst: Active Directory and Email