You may have sent formatted RTF files to recipients whose email readers cannot handle them. Use plain text in your messages instead.
Again, your recipients may be using email readers that can handle only text files. Send your messages as text, and if you need to send formatted information, send that information as a file attachment.
This occurs when you send messages using Rich Text Format (RTF) to people whose email programs cannot read RTF email messages. In Outlook, choose Tools, Options, Mail Format. Then, choose either HTML or Plain Text from the Compose in This Message Format drop-down box.
Many email systems have limitations on the size of messages they will process. Certain aspects of Word's operation can easily lead to files that are too large to be sent, and will be "bounced back" by your system's email server. To reduce file size, consider these actions:
Compress the pictures in your document (or, if the images are available on the Web, provide links instead of pictures). Right-click on a picture, choose Format Picture; click Compress; choose All Pictures in Document; and click OK.
For more information about compressing pictures, including potential drawbacks, see Chapter 13, "Getting Images into Your Documents," p. 437.
Save the document to Word 6/95 format (which generally, though not always, leads to smaller documents).
If you created the document using Word's speech or handwriting recognition features, choose Tools, Options, Save; clear the Embed Linguistic Data check box; and click OK. Then, resave the file without the accompanying voice and handwriting data that Word previously stored in it.