PHPMailer

- PHPMailer is a Free Email Transfer Class for PHP, supporting SMTP and POP3, HTML messages, attachments, and more. Sends email via sendmail, PHP mail(), QMail, or directly with SMTP.
- Download PHPMailer 5.2.1.

Example, uses PHPMailer to send email via SMTP, using a GMail account.
<?php
include('PHPMailer_5.2.1/class.phpmailer.php');

// Here sets data for email
$from = 'name@yourdomain.com';
$from_name = 'Your name';
$to = 'whoto@domain.com';
$toname = 'Receiver Name';
$subject = 'Subject for email';
$msg = 'The email message, can contains HTML tags';

$mail             = new PHPMailer();
$mail->IsSMTP();                                // telling the class to use SMTP
$mail->Host       = "smtp.gmail.com";           // SMTP server
$mail->SMTPAuth   = true;                       // enable SMTP authentication
$mail->SMTPSecure = "ssl";                      // sets the prefix to the servier
$mail->Host       = "smtp.gmail.com";           // sets GMAIL as the SMTP server
$mail->Port       = 465;                        // set the SMTP port for the GMAIL server
$mail->Username   = 'name@gmail.com';           // your GMAIL account
$mail->Password   = 'password';                 // GMAIL password

$mail->SetFrom($from, $from_name);
$mail->AddReplyTo($from, $from_name);
$mail->Subject = $subject;
$mail->MsgHTML($msg);                 // to send with HTML tags

$mail->AddAddress($to, $toname);


if(!$mail->Send()) {
  echo 'Mailer Error: '. $mail->ErrorInfo;
} else {
  echo 'Message sent!';
}
?>

Example, uses PHPMailer to send email via PHP mail(), with HTML tags and attachments.
<?php
include('PHPMailer_5.2.1/class.phpmailer.php');

// Here sets data for email
$from = 'name@yourdomain.com';
$from_name = 'Your name';
$to = 'whoto@domain.com';
$toname = 'Receiver Name';
$subject = 'Subject for email';
$msg = 'The email message, can contains HTML tags';

$mail = new PHPMailer();
$mail->SetFrom($from, $from_name);
$mail->AddReplyTo($from, $from_name);
$mail->AddAddress($to, $toname);
$mail->Subject = $subject;
$mail->MsgHTML($msg);                 // to send with HTML tags

// add attachments
$mail->AddAttachment('attachment_file.zip');      // attachment 1
$mail->AddAttachment('attachment_file.jpg');      // attachment 2

if(!$mail->Send()) {
  echo 'Mailer Error: '. $mail->ErrorInfo;
} else {
  echo 'Message sent!';
}
?>

- In the archive with PHPMailer class you'll find more examples, and documentation.
PHPMailer Web Site.