Signs a message with DKIM (RFC 6376, RFC 8463).
the whole message as it will be sent
privateKeyPem, selector, domain, algorithm and timestamp
privateKeyPem
selector
domain
algorithm
timestamp
the complete DKIM-Signature: field, without a trailing CRLF
DKIM-Signature:
Error on a key or an option that cannot make a valid signature
Signs a message with DKIM (RFC 6376, RFC 8463).