电子邮件发送在PHP上

Question

May mail is working fine but unknown sender error is showing on gmail after sending the mail. My php code is as follows

$sendto="[e-mail]";
$subject = "Payment details of ".$dmail['name'];

$message = "<br><br>";

$message .= '<table border="0" cellspacing="5" cellpadding="4" width="600"style="border-collapse:collapse; font-family:Lucida Sans; border-color:#CCCCCC">

             <tr style="background-color:#023564; color:#FFF;">
          <td colspan="2"><h3 align="center">Registration Information From Midterm Delhi CSI  2017</h3></td>
        </tr>
             <tr>
                  <td width="54%"><p>Name</p></td>
                  <td width="46%"><p>'.$dmail['name'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Age</p></td>
                  <td width="46%"><p>'.$dmail['age'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Institution</p></td>
                  <td width="46%"><p>'.$ucomp.'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Designation</p></td>
                  <td width="46%"><p>'.$dmail['designation'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Postal Address</p></td>
                  <td width="46%"><p>'.$dmail['address'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>City</p></td>
                  <td width="46%"><p>'.$dmail['city'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>State</p></td>
                  <td width="46%"><p>'.$dmail['state'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Pin</p></td>
                  <td width="46%"><p>'.$dmail['pin'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Country</p></td>
                  <td width="46%"><p>'.$dmail['country'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Phone (Off).</p></td>
                  <td width="46%"><p>'.$dmail['phone_off'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Phone (Res).</p></td>
                  <td width="46%"><p>'.$dmail['phone_res'].'</p></td>
                </tr>
                   <tr>
                  <td width="54%"><p>Mobile No</p></td>
                  <td width="46%"><p>'.$dmail['phone'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>E-mail</p></td>
                  <td width="46%"><p>'.$email.'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Gender</p></td>
                  <td width="46%"><p>'.$dmail['gender'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>Food Preference</p></td>
                  <td width="46%"><p>'.$dmail['dite'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>CSI Number</p></td>
                  <td width="46%"><p>'.$dmail['ioa_membership_no'].'</p></td>
                </tr>
                <tr>
                  <td width="54%"><p>MCI Number</p></td>
                  <td width="46%"><p>'.$csi.'</p></td>
                </tr>

                    </table>';


    $username=$dmail['name'];
    $header = "MIME-Version: 1.0
";
    $header .= "Content-type: text/html
";
    $header .= "From: ".$username."
";
    $header .="
";

    $retval = mail ($sendto,$subject,$message,$header);
    return $retval;

Answer 1

Try to add Reply-To header.

$header .= 'From: [e-mail]' . "
";
$header .= 'Reply-To: [e-mail]' . "
";

OR with name:

$header .= 'From: "From Name" <[e-mail]>' . "
";    
$header .= 'Reply-To: "From Name" <[e-mail]>' . "
";