PHP email validation

Question

For PHP what is the best email validation using preg, NOT ereg because it's deprecated/removed.

I don't need to check if the website exists (it's not like maximum security).

I've found many ways with ereg but they (obviously) aren't good practice.

Answer 1

I suggest you use the FILTER_VALIDATE_EMAIL filter:

if (filter_var($email, FILTER_VALIDATE_EMAIL)) {
    //valid
}

You can also use its regular expression directly:

"/^(?!(?:(?:\\x22?\\x5C[\\x00-\\x7E]\\x22?)|(?:\\x22?[^\\x5C\\x22]\\x22?)){255,})(?!(?:(?:\\x22?\\x5C[\\x00-\\x7E]\\x22?)|(?:\\x22?[^\\x5C\\x22]\\x22?)){65,}@)(?:(?:[\\x21\\x23-\\x27\\x2A\\x2B\\x2D\\x2F-\\x39\\x3D\\x3F\\x5E-\\x7E]+)|(?:\\x22(?:[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F\\x21\\x23-\\x5B\\x5D-\\x7F]|(?:\\x5C[\\x00-\\x7F]))*\\x22))(?:\\.(?:(?:[\\x21\\x23-\\x27\\x2A\\x2B\\x2D\\x2F-\\x39\\x3D\\x3F\\x5E-\\x7E]+)|(?:\\x22(?:[\\x01-\\x08\\x0B\\x0C\\x0E-\\x1F\\x21\\x23-\\x5B\\x5D-\\x7F]|(?:\\x5C[\\x00-\\x7F]))*\\x22)))*@(?:(?:(?!.*[^.]{64,})(?:(?:(?:xn--)?[a-z0-9]+(?:-[a-z0-9]+)*\\.){1,126}){1,}(?:(?:[a-z][a-z0-9]*)|(?:(?:xn--)[a-z0-9]+))(?:-[a-z0-9]+)*)|(?:\\[(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){7})|(?:(?!(?:.*[a-f0-9][:\\]]){7,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,5})?)))|(?:(?:IPv6:(?:(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){5}:)|(?:(?!(?:.*[a-f0-9]:){5,})(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3})?::(?:[a-f0-9]{1,4}(?::[a-f0-9]{1,4}){0,3}:)?)))?(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))(?:\\.(?:(?:25[0-5])|(?:2[0-4][0-9])|(?:1[0-9]{2})|(?:[1-9]?[0-9]))){3}))\\]))$/iD"

But in that case, if a bug is found in the regular expression, you'll have to update your program instead of just updating PHP.

Answer 2

Unless you want to use a very very long regular expressions you'll run into valid email addresses that are not covered (think Unicode). Also fake email addresses will pass as valid, so what is the point of validating if you can simply write test@test.com and get away with it?

The best way to validate email addresses is to send a confirmation email with a link to click. This will only work if the email address is valid: easy, and no need to use regex.

Answer 3

function check_email($check) {
$expression = "/^[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]+\.([a-zA-Z]{2,4})$/";
if (preg_match($expression, $check)) {
    return true;
} else {
    return false;
} 
}

Call it in if() condition as below example :

if(!check_email($_REQUEST['ContactEmail'])){
  $register_error ="Enter the correct email address!<br />";
  $reg_error=1; 
}