How to validate an email address

Short answer

filter_var() returns the address if it is valid and false if not:

<?php
 
var_dump(filter_var('anna@example.com', FILTER_VALIDATE_EMAIL) !== false);
var_dump(filter_var('anna@example', FILTER_VALIDATE_EMAIL) !== false);

Output:

bool(true)
bool(false)

Before saving

Trim the spaces and lowercase the address so that the same address is not saved twice:

<?php
 
$email = strtolower(trim('  Anna@Example.COM '));
 
echo $email;

Output:

anna@example.com

What the check does not guarantee

A valid format does not mean the mailbox exists. There is only one way to be sure — send an email with a confirmation link.