In the Universal Email behavior, click the envelope icon to go to the SMTP server settings screen.
in the SMTP server settings screen, set the Character set to ISO-8859-1
I would not suggest this. ISO-8859-1 is outdated, but still used in English speaking countries. If you'll ever come accross lets say a Polish character like "Ł" you'll be lost again with ISO-8859-1. UTF-8 should be your choice. Make sure that you deliver it inthe right mode, especially if using HTML