PHPMailer is a PHP email transport class

PHPMailer is a PHP email transport class featuring file attachments, SMTP servers, CCs, BCCs, HTML messages, word wrap, and more. Sends email via sendmail, PHP mail(), QMail, or directly with SMTP. Support for additional transports, such as SMS, MMS will be forthcoming

Reference:
http://code.google.com/a/apache-extras.org/p/phpmailer/