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In Firefox 6, I use the Proxy Tool add on to spoof my user agent and platform strings as part of my effort to improve privacy.

Is there an equivalent for emails sent from Thunderbird 6? If so, how do I do it?

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up vote 3 down vote accepted

Add the preference: general.useragent.override (Source)

Step by step with screenshots

Open the Config Editor by using "Options" from the "Tools" main menu point:


then go to the "Advanced" settings and there the "General" tab:


and click the button labeled "Config Editor", which will bring up this dialog (unless you suppressed it earlier):

Warning dialog

If in the window that opens (title about:config) the search for general.useragent.override yields nothing, right-click into the white space which contained the list of preferences before you started your search and choose "New" and "String":

New String menu

in the dialog that opens, enter general.useragent.override as the preference name:

New string dialog

and finally in the next dialog enter the desired user agent string to override with, for example:

  • Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0

or leave it empty if you want to. A list of actual user agent strings for Thunderbird can be found here.

Additional tokens in the user agent string

I have noticed that the Lightning extension adds its own token to the user agent string, so beware of that.

If you want to get rid of that as well, empty the following string values in the Config Editor (window titled: about:config) which you had opened in the above steps.

Relevant preference names:

  • calendar.useragent.extra for the Lightning calendar extension
  • general.useragent.extra.thunderbrowse for the ThunderBrowse extension
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Thank you for your answer! – hpy Jul 17 '12 at 14:08

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