Fixed a bug where mail messages were malformed when using the Sendmail

transport on Unix systems with certain versions of sendmail (e.g.
Postfix < 2.9). Specifically, message headers spilled into the body
and the body text was double-spaced.

The source of the problem was the use of CRLF as the EOL sequence
when sending messages via PHP's built-in mail() function on Unix
systems. Despite what the PHP manual says, LF should be used as the
sole EOL character on Unix. This is because mail() is a wrapper for
sendmail on Unix and does not speak SMTP except on Windows.

See http://zend-framework-community.634137.n4.nabble.com/Zend-Mail-and-Postfix-lt-2-9-td4658920.html for further discussion.