These Properties have the following priorities for displaying (if available):
PR_RTF_COMPRESSED or PR_HTML
PR_BODY
So, if in message two properties have been filled, for instance PR_RTF_COMPRESSED and PR_BODY, and you open this message in MS Outlook, outlook displays information from PR_RTF_COMPRESSED. Similarly, if a message has PR_HTML and PR_BODY properties and you open this message in MS Outlook, Outlook displays information from PR_HTML. In both cases, PR_BODY property won’t be used to display text.
I hope the information is useful for your requirements and please feel free to write to us in case you have any further query about these.