PHP: Verify And Sanitize Email Address

Q. How do I verify input data such as email address under PHP programming language?

A. You need to use PHP Filters designed for safely dealing with input parameters. It can validate and filter data coming from some insecure source, such as user input via filter extension. This extension is part of PHP Core version 5.20 and above, but you can always install it under Linux. You can use filters to validate following type of data:

=> regex
=> url
=> email
=> strings
=> magic_quotes
=> regular data types such as int, float etc

Validate email address

Here is a sample code:

<?
$email="[email protected]";
if ( filter_var($email, FILTER_VALIDATE_EMAIL)  == TRUE) {
	echo 'Valid Email Address';
}
else
{
	echo 'Invalid Email Address';
}
?>

<?
$email="[email protected]";
if ( filter_var($email, FILTER_VALIDATE_EMAIL) == TRUE) {
echo ‘Valid Email Address’;
}
else
{
echo ‘Invalid Email Address’;
}
?>

filter_var() will filter a variable with a specified filter. In this case you’ve used FILTER_VALIDATE_EMAIL filter. You may also want to sanitizes the e-mail using following code:

$out=filter_var($email, FILTER_SANITIZE_EMAIL);

$out=filter_var($email, FILTER_SANITIZE_EMAIL);

Here is another sample:

<?php
// form.php
//....
//......
$_POST['email'] = stripslashes(trim($_POST['email']));
$tmpEmail=filter_var($_POST['email'], FILTER_SANITIZE_EMAIL);
if ( filter_var($tmpEmail, FILTER_VALIDATE_EMAIL)  == TRUE) {
	// callSmtp
	fireSmtp();
}
else{
	//show error
	echo 'Invalid Input - an error has occurred when trying to send this email';
}
///....	
 
?>

<?php
// form.php
//….
//……
$_POST[’email’] = stripslashes(trim($_POST[’email’]));
$tmpEmail=filter_var($_POST[’email’], FILTER_SANITIZE_EMAIL);
if ( filter_var($tmpEmail, FILTER_VALIDATE_EMAIL) == TRUE) {
// callSmtp
fireSmtp();
}
else{
//show error
echo ‘Invalid Input – an error has occurred when trying to send this email’;
}
///…. ?>

Further readings:

Posted by: SXI ADMIN

The author is the creator of SXI LLC and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.