md_arc_sign
Returns an hash with mail headers and the ARC signature for the
message. If ARC sign fails the hash will contain an error message.
The method accepts the following parameters:
$keyfile
The path to the private ARC key
$algorithm
The algorithm to be used to sign the message, by default is
'rsa-sha256'
$chain
The cv= value for the Arc-Seal header. "ar" means to copy it
from an Authentication-Results header, or use none if there
isn't one.
$domain
The domain to be used when signing the message.
$srvid
The authserv-id in the Authentication-Results headers, defaults
to Domain.
$selector
The selector to be used when signing the message, by default
it's 'default'
$headers
The headers to sign, by default the headers are: From Sender
Reply-To Subject Date Message-ID To Cc MIME-Version Content-Type
Content-Transfer-Encoding Content-ID Content-Description
Resent-Date Resent-From Resent-Sender Resent-To Resent-cc
Resent-Message-ID In-Reply-To References List-Id List-Help
List-Unsubscribe List-Subscribe List-Post List-Owner
List-Archive