>In my opinion it makes no sense in signing your email (whether it is S/MIME or DKIM) to prove that the email is authentic, and then complaining that there is n

>In my opinion it makes no sense in signing your email (whether it is S/MIME or DKIM) to prove that the email is authentic, and then complaining that there is no way to deny that the email is authentic once stuff goes bad. We all understand that really only the domain part is being authenticated, but if people believe in the good user identity and authentication practices of the sending domain then it's going to hard to rebut the presumption that the email is from the apparent sender. If we posit that the purpose of DKIM signatures is preventing the injection of forgeries in the MTA chain, then authenticity is only an important property from the time that the message is sent until the time it reaches its addressed recipient. After that point, it's a bug, because long-term non-repudiation is not a purpose of DKIM. Once a particular message is no longer traversing the network, there is no value (for DKIM purposes) in preserving the secrecy of the signing key.