Hexamail Guard Administration Guide - DKIM Selector - ADSP
Author Domain Signing Practices
The legacy of the Internet is such that not all messages will be signed, and the absence of a signature on a message is not
an a priori indication of forgery. In fact, during early phases of deployment it is very likely that most messages will remain unsigned.
However, some domains might decide to sign all of their outgoing mail, for example, to protect their brand names.
It is desirable for such domains to be able to advertise that fact to other hosts.
This is the topic of Author Domain Signing Practices (ADSP).
Hosts implementing this specification can inquire what Author Signing Practices a domain advertises.
This inquiry is called an Author Signing Practices check.
If you make the DNS entries specified in your DNS management console you can insist that some email (unknown) or all email (All) be signed
and remote servers will take appropriate action when they detect email that is not signed but should be.
If you specify Discardable it means you are happy for email from your domain to be discarded if it is not signed.
DNS Entries Required