$_POST returning empty value - php

Question

EDIT: The code seems to work if I place the PHP code in the same file at the HTML. I'll implement this method for now. Thank you for the help!
Whenever I try to echo the values in a PHP file from an input box the values appear to be empty.
Here is my HTML code
<form action="sendmail.php" method="post">
<label>Name:</label><br>
<input name="person" type="text" /><br>
<label>Email:</label><br>
<input name="email" type="email" /><br>
<label>Opportunity:</label><br>
<textarea name="message" rows="8"></textarea><br>
<input type="submit" value="Submit" class="button">
</form>
This is my sendmail.php file
$name = $_POST['person'];
$email = $_POST['email'];
$message = $_POST['message'];
echo $name;
echo $email;
echo $message;

Answer 1

You can get the value in Your current page itself
<?php
if(isset($_POST['person']))
{
$name = $_POST['person'];
$email = $_POST['email'];
$message = $_POST['message'];
echo "Name".$name;
echo "Email".$email;
echo "Message".$message;
}
?>
<form action="" method="post">
<label>Name:</label><br>
<input name="person" type="text" /><br>
<label>Email:</label><br>
<input name="email" type="email" /><br>
<label>Opportunity:</label><br>
<textarea name="message" rows="8"></textarea><br>
<input type="submit" value="Submit" class="button">
</form>
or if you want the data in another page
<form action="send.php" method="post">
<label>Name:</label><br>
<input name="person" type="text" /><br>
<label>Email:</label><br>
<input name="email" type="email" /><br>
<label>Opportunity:</label><br>
<textarea name="message" rows="8"></textarea><br>
<input type="submit" value="Submit" class="button">
send.php file
<?php
if(isset($_POST['person']))
{
$name = $_POST['person'];
$email = $_POST['email'];
$message = $_POST['message'];
echo "Name".$name;
echo "Email".$email;
echo "Message".$message;
}
?>

Answer 2

I tried this code and it worked fine, so whatever is wrong it is not with the code you have pasted here.
to make sure the post is successful, try this:
if(isset($_POST['person']))
echo "passed fine.";

Answer 3

check:
if (strtoupper($_SERVER['REQUEST_METHOD']) == 'POST'){
if(isset($_POST['person'])){
$name = $_POST['person'];
echo $name;
}
}
else{
echo"Your form submission is not correct";
}

Answer 4

try this code.
HTML
<form action="sendmail.php" method="post">
<label>Name:</label><br>
<input name="person" type="text" /><br>
<label>Email:</label><br>
<input name="email" type="email" /><br>
<label>Opportunity:</label><br>
<textarea name="message" rows="8"></textarea><br>
<input type="submit" value="Submit" class="button">
</form>
PHP
<?php
$name = $_POST['person'];
$email = $_POST['email'];
$message = $_POST['message'];
echo $name;
echo $email;
echo $message;
?>

Answer 5

<form action="456.php" method="post">
<label>Name:</label><br>
<input name="person" type="text" /><br>
<label>Email:</label><br>
<input name="email" type="email" /><br>
<label>Opportunity:</label><br>
<textarea name="message" rows="8"></textarea><br>
<input type="submit" value="Submit" class="button">
</form>
<?
print_r($_POST);
?>