The Mail pane of the Preferences. This pane is seen only in the document Preferences dialog.
Configuring this feature allows email to be sent to Tinderbox.
As from v5.10.2, this feature is temporarily disabled, pending new network interface code. In the interim, it is suggested to use Simplenote sync. Simplenote includes a reliable email interface whose input can then be synched from Simplenote to Tinderbox. New documents made in v5.10.2 lack this preference pane; it will still be shown when opening documents made in earlier versions, although the associated features may not work in v5.10.2+.