I use this class for sending e-mail: http://www.phpguru.org/downloads/Rmail/Rmail%20for%20PHP/docs.html
It was working until I switched from "mail" to SMTP. Now, if I use setHtml($html) it works, but if I also use setText($text), it doesn't work.
Can it be that $text contains some invalid characters? Why would those characters work when using the system "mail", but not work on SMTP running on localhost?