注意：未定义的变量：第9行中的MESSAGE_BODY

Question

I have a simple contact page set up with a form and I am sending those details via email using the php mail() function. When I submit the page its die and says:

Notice: Undefined variable: MESSAGE_BODY in line 9

Anybody has any idea or solution please?

 <?php
 error_reporting(E_ALL); 
if ($_POST["email"]<>'') {
    $ToEmail = '[e-mail]';
    $EmailSubject = 'Get an instant Quote Now';
    $mailheader = "From: ".$_POST["email"]."
";
    $mailheader .= "Reply-To: ".$_POST["email"]."
";
    $mailheader .= "Content-type: text/html; charset=iso-8859-1
";
    $MESSAGE_BODY .= "Company Name".$_POST['companyname']."";
    $MESSAGE_BODY = "First Name: ".$_POST["firstname"]."";
    $MESSAGE_BODY = "Last Name: ".$_POST["lastname"]."";
    $MESSAGE_BODY .= "Email: ".$_POST["email"]."";
    $MESSAGE_BODY = "Phone Number: ".$_POST["phone"]."";
    $MESSAGE_BODY = "Delivery City: ".$_POST["city"]."";
    $MESSAGE_BODY = "Delivery Date: ".$_POST["date"]."";
    $MESSAGE_BODY = "Duration: ".$_POST["duration"]."";
    $MESSAGE_BODY .= "Rental Equipment: ".nl2br($_POST["msg"])."";
    mail($ToEmail, $EmailSubject, $MESSAGE_BODY, $mailheader) or die ("Failure"); 
 ?>

 Your message was sent
<?php
} else {
?> 
 <aside>
          <form action="./" method="post" class="form-c">
            <fieldset>
              <legend>Get an Instant Quote Now</legend>
             <p>
              <label for="companyname">Company Name</label>
              <input type="text" id="companyname" name="companyname" required>
            </p>
             <p>
              <label for="firstname">First Name</label>
              <input type="text" id="firstname" name="firstname" required>
            </p>
             <p>
              <label for="lastname">Last Name</label>
              <input type="text" id="lastname" name="lastname" required>
            </p>
             <p>
              <label for="email">Email Address</label>
              <input type="email" id="email" name="email" required>
            </p>
            <p>
              <label for="phone">Phone</label>
              <input type="number" id="phone" name="phone" required>
            </p>
             <p>
              <label for="city">Delivery City</label>
              <input type="text" id="city" name="city" required>
            </p>
             <p>
              <label for="date">Delivery Date</label>
              <input type="text" id="date" name="date" required>
            </p>
            <p>
              <label for="durationa">Duration</label>
              <input type="text" id="duration" name="duration" required>
            </p>

            <p>
              <label for="msg">Enter Rental Equipment</label>
              <textarea id="msg" required="" name="msg"></textarea>
            </p>

              <p class="submit"><button type="submit" name="submit">Proceed</button></p>
            </fieldset>
          </form>

          <?php
};
?>

        </aside> 

Answer 1

Use isset. Fisrt line should be:

if (isset($_POST["email"]) && $_POST["email"] != "") {

This will trigger a short-cirtuit evaluation of && and the second condition will not cause error if the "email" field is not sent.