How to check that send email is open by receiver or not
If we send email use Php mail() function and want that you get information when receiver open that mail or want to keep record of open mail send in mass sending of mail using Php mail() function. To do that we use following code.
$to=""; //email receiver id
$subj=""; // subject of mail
$msg=""; // message that send to receiver
$senderheaders = "From: email@example.com\r\n";
$senderheaders .= "Content-type: text/html\r\n";
$senderheaders.="<img src=\"http://www.example.com/trackemail.php?receiverId=$id\" width=\"1\" height=\"1\" />";
In above code we send image of 1*1px with the header of the mail. when receiver open that mail that will send back to tracking file of sender site and tell them that email is check by receiver.