Mail.app of OS X 10.4 shows some letters garbled, e.g. instead of ä, ö, ø, å, è, é, ñ, ã, õ.

Mail.app of OS X 10.4 shows some letters garbled, e.g. instead of ä, ö, ø, å, è, é, ñ, ã, õ. The mail receiver sees letters as squares, symbols, Asian characters or other wrong encoding.

User side is often PC (Windows, Linux; Outlook, Outlook Express, Thunderbird, Kmail and so on); sometimes even Mac OS X 10.4, 10.3, 10.2, 10.1, OS 9.x, 8.x.

Verify if it is caused by a bad font. Mac OS X fonts list and Turning fonts off can be useful.

Unfortunately some of the people annoyed by this are graphics and other who have a need for hundreds of fonts, and who are unwilling to find a font among hundreds or thousands to be the problem; enabling then half of the fonts back, then some more and so on until a bad one would have been identified. And in some cases the problem is not a bad font but something else.

What seems the ultimate solution - here. Just take normal Terminal or command line precaution: careful with what you type. A letter MAKES a difference.

Locate Terminal in your Applications > Utilities folder. Open it.

Enter in terminal window:

defaults write com.apple.mail NSPreferredMailCharset "UTF-8"

(including the "") and press enter.
Now it should behave correct.