Thursday, January 9, 2003 02:57 PM
I don't think there's any Internet standard for such a concept. Look at the headers of other messages which are displayed in the way you like, in your email client.
Different email clients will vary in how they interpret headers, in which header they are looking for, and what value in it, to change their display of the caption of a given message e.g. changing its color, adding a flag or otherwise tagging it in the GUI interface.
Decide which header you are interested in, and what value for it (based on how your experiments turn out with other messages) and add that header, with the right value, before sending the message.
For example, again there is no standard, but I think some email client applications will look for headers with names like "Priority", "Importance", "Sensitivity", "Precedence", "Mood" etc. and will display the caption differently according to what value is found there. So try to match what they want, with the header name and value that you add to your message.