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:

<?
$email="vivek@nixcraft.com";
if ( filter_var($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);

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';
}
///....	
 
?>

Further readings:

• PHP Filter

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