Tried to post some HTML contents, actually a complete HTML page, as a reply to another message. After submiting the message, the browser window showed that the message was posted with the message ID. However, the message disappeared if the Refresh link on the same window was clicked, and could not be found using the search feature either.

In order to post them, one have to:
1. Reply the message
2. Type in the Subject and something in the Contents box.
3. Submit the message
4. Modify the message to replace the Contents with the actual HTML contents.
5. Submit the message again.

Please see message 607601 and 607619 for example.