Sensitivity Header + SPX 0.2a Requires Restart
by heiligkuh
Implement the "Sensitivity" header for outgoing messages (described in RFC 4021 section 2.1.55).
Forked from another add-on developed by ff_bob, added SPX header for Sophos security appliances
About this Add-on
This simple addon currently allows the user to add a sensitivity indicator ('Personal/Private/Company-Confidential') to an outgoing message via an option in the tools menu, or from an optional drop-down toolbar menu (similar to message priority).
While adding this header does not directly add any security to the message, the header can be interpreted by some MTA/MUAs such that the message is treated differently while in transit, or when viewed by the recipient:
- e.g. MS Outlook/Exchange: Can be set so that confidential/personal messages are unable to be read by the recipient's delegated users; A warning can be displayed before the message is forwareded; Displays an advisory message above content.
- e.g. Some versions of Symantec PGP in corporate set-ups can automatically encrypt the outgoing message if leaving the corporate network, or redirect it to a secure corporate webmail page (with an automated notification email to the recipient to collect it there).
Known Issues
When re-opening a draft message where a sensitivity was set, the previous value is not currently retained (this does not effect the SPX header, that one sticks). Similarly, when forwarding or replying to a message, the sensitivity value from the original message is not currently retained. As such, please make sure to select the correct sensitivity before sending your messages - if you add the toolbar item, this is always visible when composing. I hope to find a fix for these issues in a future version.
This addon does not currently show an indicator for received messages yet - In future versions of this addon, I may add some kind of (optional) banner above the message when the header is set to Personal/Private/Confidential. In the meantime, if the header has been set on any message, it will be visible if 'View Menu -> Headers -> All' is ticked.
If you're familiar with Thunderbird addon development or can help with translations, and would like to help out, please get in touch (heiligkuh gmail com).
Development Plan
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TODO: When editing a draft, or replying to a message with this header, make the header in the new message the same.
TODO: Add the toolbar item automatically on install.
TODO: Display an (optional) banner above received message (if header is set to priv/pers/conf).
TODO: Automatically add the header to the searchable headers list. (and remove it on uninstall).
//user_pref("mailnews.customHeaders", "Sensitivity"); // ADD it to list of searchable message fields.
TODO: Keep UI strings localised where possible.
TODO: When the selected sensitivity is 'normal' when composing, remove the custom header completely.