Why does the rmail-php-class fail if I setText(), but works if I only setHtml()?

I use this class for sending e-mail: http://www.phpguru.org/downloads/Rmail/Rmail%20for%20PHP/docs.html

It was work开发者_如何学Cing 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?

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It turns out "\n" characters (LF) are not allowed, only "\r\n" (CRLF) is acceptable in the e-mail text body.

Somehow among all the CRLF pairs one LF sneaked in, which caused the sending to fail.

Aren't bytes wonderful?