PHP，设置退回电子邮件地址

When using PHP to send email, how can I set the return path for receiving bounced back emails?

There is a parameter in mail() that allows user to set additional headers. You should set a "Return-Path" header, like this:

mail($email, $subject, $message,
"From: $returnaddress
"
. "Reply-To: $returnaddress
"
. "Return-Path: $returnaddress");  

To get this to work on my server (bluehost) I had to also use the fifth parameter (i.e. "$additional") as shown below:

     $headers = "From: joe.smith@shaw.ca
Reply-To: joe.smith@shaw.ca";

     $additional = "-rjoe.smith@shaw.ca";

     mail("fred.jones@shaw.ca", "Subject", "Message",$headers, $additional);