电子邮件确认“来自”字段无效

Question

The following is code on my site for sending a confirmation email when the user signs up. The email gets sent just fine but the sender is blank (it comes up as "unknown sender"). I would like it to come from my email, from ABC Technologies.

{
// ---------------- SEND MAIL FORM ----------------
// send e-mail to ...
$to=$user;
// Your subject
$subject="Your confirmation link here";

// From
$header="from: ABC Technologies";
// Your message
$message="Confirmation link for college match site
";
$message.="Click on this link to activate your account 
";
$message.="http://$_SERVER[HTTP_HOST]/chat_site/confirmation.php?passkey=$confirm_code";
// send email
$sentmail = mail($to,$subject,$message,$header, "-f ABC Technologies");
}

Answer 1

Correct, this is not a valid sender:

$header="from: ABC Technologies";

You're obviously missing the email address:

$header="from: ABC Technologies <[e-mail]>";

Additionally, this is not a valid return path:

"-f ABC Technologies"

Now you need an email address; not even an email+name combination, just an email:

"[e-mail]"