Values.EnvelopeSourceThe SMTP envelope information of the email.
type nonrec t = {helo : String_.t option;The HELO used by the host from which the email was received.
*)from : String_.t option;The RCPT FROM given by the host from which the email was received.
*)to_ : StringList.t option;All SMTP TO entries given by the host from which the email was received.
*)}