Values.AddHeaderActionSourceThe action to add a header to a message. When executed, this action will add the given header to the message.
type nonrec t = {headerName : HeaderName.t;The name of the header to add to an email. The header must be prefixed with "X-". Headers are added regardless of whether the header name pre-existed in the email.
*)headerValue : HeaderValue.t;The value of the header to add to the email.
*)}