Thunderbird:Help Documentation:Hidden Preferences

Warning: This page is infrequently updated, and typically out of date.

Hidden preferences (or just hidden prefs) are preferences that cannot be changed in Thunderbird's Options Window or some other nice GUI. They are stored together with all other settings in a file named prefs.js in your profile directory. You can edit this file directly or use Thunderbird's config editor (recommended). See Editing Configuration Files for details.

This page should become an overview of all hidden prefs used by Mozilla Thunderbird, containing short descriptions and possibly links to detailed documentation.

mail.compose.other.header
Type: string
Default value: none
Version: unknown
Comma separated list of header fields that can be added in composer in addition to To, Cc, Bcc...

mail.identity.*.replyto_mangling_mailing_lists
Type: string
Default value: none
Version: Thunderbird 3.0 beta 1
Comma separated list of mailing lists that mangle Reply-To header field and that you post messages to. Used to automatically set Mail-Reply-To header field. See Mail-Followup-To and Mail-Reply-To for details.

mail.identity.*.subscribed_mailing_lists
Type: string
Default value: none
Version: Thunderbird 3.0 beta 1
Comma separated list of subscribed mailing lists. Used to automatically set Mail-Followup-To header field. See Mail-Followup-To and Mail-Reply-To for details.

mail.strict_threading
Type: boolean
Default value: false
Version: unknown
Set to true to not thread by subject. Overrides mail.thread_without_re. See Stop threading by subject

mail.thread_without_re
Type: boolean
Default value: true
Version: unknown
Set to false to not combine messages with same subjects into the same thread if none of them start with "Re:" See Stop threading by subject

mailnews.nav_crosses_folders
Type: integer
Default value: 1
Version: unknown
Specifies how to handle the "Advance to next unread message in <x>" folder prompt.
0: Always go to the next folder without prompting
1: Ask before going
2: Don't prompt and don't go to the next folder