PHP: How to validate an email address with PHP

There are a lot of cases in which you will need to check for a valid email address. For example, you might have a user registration script, an online newsletter or a simple contact form. As merely humans, subscribers to our online newsletters might inadvertently misspell their email address, forget to press and hold the Shift key to get the @ character or miss to press the period before the “com”. Whatever the mistake the user makes, our script must be prepared.