Q: PHP - multiple email addresses Here is my php so far
$headers  = "From: webinquiries@someplace.com\n";
$headers .= "Reply-To: sales@someplace.com\n";
$headers .= 'Bcc: someone@someplace.com' . "\r\n";
$headers .= "MIME-Version: 1.0\n";
$headers .= "Content-Type: text/plain; charset=ISO-8859-1\n";
mail($to, $subject, $body, $headers);

how do i add three more email addresses to this list

A: You can pass a string with comma-separated e-mail addresses, or any other string that complies with RFC 2822.
Please read the mail function documentation in the PHP manual.

A: Create an array of email addresses, loop through each item in the array and call the mail() function. Or submit a comma separated list like so User <user@example.com>, Another User <anotheruser@example.com>.
If your emailing 'needs' require sending an extensive amount of emails, you might want to look into some third party libraries, as the mail function is very 'delicate'.

A: Use something like Swiftmailer or PHPMailer - they eliminate the hard work in creating MIME-based emails, and allow any number of To/CC/BCC addresses in any combination.
