Phat writes:
So how did I mess it up? (hopefully I will learn not to make that mistake again)
Previewing before submitting will usually reveal most problems. In this case the close angle bracket of </iframe> was on the next line, i.e.:
</iframe
>
This would be okay in an HTML file but not in a message because the message processing code translates a linefeed into <br>, so it ended up as <iframe<br>>, which is badly formed HTML and is ignored, thus leaving an unterminated <iframe>.
--Percy