Is Postfix capable of checking DKIM and SPF records on incoming email and adding headers based upon its findings?
Not the postfix code itself, but postfix supports milters which do this.
My google searches have only returned results on how to do DKIM signing on outbound email and not how to verify them on inbound emails.
The milter that does the signing usually will also verify signatures on incoming, for example is OpenDKIM.
