Use Exchange Rich Text Format
If enabled, IMAP4 clients receive messages in Exchange rich-text format. Although all IMAP clients receive the information as an attachment, the attachment is opened and displayed as a normal message for IMAP clients that can interpret Exchange RTF. For IMAP clients that cannot interpret Exchange RTF, an attachment is displayed. By default, Exchange RTF is not used.
To enable Exchange Rich Text Format:
Note If you want to use Exchange rich-text format, the only MIME option available is plain text.