108153, 30888, 69529, 126082:

New HTML message body options for Mailnews
Provide a work around / fix for some of the security and usability problems that HTML mails currently impose, by not rendering everything the sender throws at the user.

We achieve that by either
- removing offending HTML tags/attributes
- converting HTML to plaintext and back to HTML or
- rendering the HTML source.

This is the pref UI, a View submenu

suite/locales/en-US/chrome/mailnews/messenger.dtd

@@ -198,6 +198,14 @@ Rights Reserved.
 <!ENTITY headersNormalCmd.accesskey "N">
 <!ENTITY headersBriefCmd.label ".Brief">
 <!ENTITY headersBriefCmd.accesskey "B">
+<!ENTITY bodyMenu.label "Message Body as">
+<!ENTITY bodyMenu.accesskey "O">
+<!ENTITY bodyAllowHTML.label "Original HTML">
+<!ENTITY bodyAllowHTML.accesskey "H">
+<!ENTITY bodySanitized.label "Simple HTML">
+<!ENTITY bodySanitized.accesskey "S">
+<!ENTITY bodyAsPlaintext.label "As Plain Text">
+<!ENTITY bodyAsPlaintext.accesskey "P">
 <!ENTITY viewAttachmentsInlineCmd.label ".View Attachments Inline">
 <!ENTITY viewAttachmentsInlineCmd.accesskey "A">
 <!ENTITY reloadCmd.label "Reload">