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Whenever I compose a new email message in Thunderbird, it defaults to the Western (ISO-8859-1) encoding, and I have to manually change it to UTF-8 every time.

How do I change the default?

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up vote 40 down vote accepted

Tools → Options → Display → Formatting → Fonts → Advanced... → Character Encodings → Outgoing Mail:


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Aha! Thanks! – hpy May 26 '11 at 15:30
Well, that is somewhat illogical to put it there … Thanks! – Martin Ueding Mar 31 '12 at 20:22
In linux it's Edit > Preferences > Display... – ChocoDeveloper Feb 2 '13 at 3:20
Agreed that it's illogical : you'd expect it to be in "Composition", not "Display". Completely defeats principle of least surprise. They could at least adopt a prefs dialog like Eclipse that will filter to aid discovery of obtuse settings. – Adrian Dec 1 '14 at 15:40

For Thunderbird 17 on the Mac, you can find this setting at:

Thunderbird > Preferences > Display > Formatting > Advanced

Look at the Character Encodings section, as seen here:

enter image description here

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Regarding your comment; I did test it and it is the very same path, only with Edit except Thunderbird under Icedove@Debian and the dialog also looks the same (except for the theme, obviously). – bitmask Jun 27 '13 at 5:32
Great. Add a new answer with screenshot. – james.garriss Jun 27 '13 at 12:32

On Mac OS X you have to use the Config Editor (also know as about:config) found in Preferences -> Advanced -> General. Change the value of the preference named mailnews.send_default_charset to UTF-8.

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