Go to Word's menu Tool - AutoCorrect, uncheck all selections. You will have no such trouble if you use Netscape rather than Microsoft Internet Explorer. Viewing Mail, you can choose if you want to use the Microsoft Viewer. But it didn't work. Otherwise, click on it to select your language.
English text is composed of single-byte words with spaces separating the words.
When a long Chinese line is wrapped wrongly in the middle of a character, a whole line of Chinese text will be corrupted. You can edit the corrupted line by removing one half character at the front of the line. Or you can ask your friend to send Chinese message with pre-wrapped shorter lines. The email received from my Chinese friends contains corrupted Japanese-like symbols. The problem is caused by the fact that there is no spaces in between Chinese characters as English text do.