Launching Firefox from Thunderbird adds backslashes to addresses

From MozillaZine Knowledge Base

This article deals with Firefox adding an additional two backslashes when opened from links in Thunderbird - for example a link to becomes http://\\

  • Check to see if Thunderbird is being launched in compatibility mode - Right click the Thunderbird shortcut, go to the Compatibility tab, and uncheck everything.[1]
  • The Netscape Mail Notifier may cause the problem.[2]

Note that uninstalling and reinstalling Thunderbird does not reset the compatibility setting, the new Thunderbird version will "inherit" that setting. Also, be advised that Thunderbird 3.0 (and likely other Gecko 1.9 applications) will not start up in compatibility mode.

Related Bug

Bug 381922 – clicking any email link in TB2.0 gives exta \\ in firefox url box.