title: What is the RFC 822 format for the email addresses?
body: <p>I have to make a regular expression for the email addresses (RFC 822) and I want to know which characters are allowed in the local part and in the domain.</p>
  <p>I found this <a href="https://www.rfc-editor.org/rfc/rfc822#section-6.1" rel="nofollow noreferrer">https://www.rfc-editor.org/rfc/rfc822#section-6.1</a> but I don't see that it says which are the valid characters.</p>