Why does Evolution not display exotic / umlaut / accented characters in received emails?
If the email program of the sender is broken or misconfigured, plain text emails sent do not include information about the character encoding used. If you receive such messages, change the character encoding from “Unicode” to an appropriate one (for example “Western European”) by choosing “View | Character Encoding” from the main menu. You might have to guess which encoding is the “appropriate” one. You have to make this change every time you view the message.