Quick post – date and time format of messages displayed in Thunderbird can be controlled in two simple ways. This is useful if you’ve noticed Thunderbird using the bizarre US format (e.g. MM/DD/YYYY). This is on OpenIndiana, but is just as applicable for any Gnome 2-based environment.
First, the “LC_TIME” variable can be set in a user’s profile file (e.g. ~/.profile if using bash or ksh). Let’s specify New Zealand English:
export LC_TIME="en_NZ.UTF-8"
Log out and log back in, fire up Thunderbird and messages should now be using the DD/MM/YYYY format.
The second method is much simpler. Thunderbird actually uses the system language settings for message date and time display formatting. So, if you’ve never noticed that little language setting before on the Gnome login screen, now would be the time to change it to the language of your choice:
Thunderbird will then use a sane format.

