If you would like to send mail notifications with HTML code enabled,

A subject like :
Code:
<Font Color=#ff0000> xxxxxx </font>
It's possible in ADMON, you need to do it with a change in the file src/libs/email/email.c,

At line 219, make some adjustings:

Code:
"Content-Type: text/plain; charset=\"UTF-8\"\r\n"
Change text/plain to text/html in that line, recompile the source code and it's done.