While we aren't defining reputation or accreditation services in this working group, it has been widely suggested that such services would use the d= domain on the signature as the "lookup key" for retrieving reputation or accreditation information.
There is a fundamental difference, then, between key delegation and delegation via SSP. In the former (key delegation) case, the party applying the signature (delegatee) is merely acting as an agent of the delegator to do the mechanics of signature application. It is still the delegator's signature, and the "buck stops" with the delegator in terms of who has taken responsibility for the message. In the latter (SSP delegation) case, it is the delegatee's domain that takes responsibility for the message. Some have suggested the delegatee might want to use subdomains in order to allow reputations to avoid aggregating reputations from different delegators (or classes of delegators). Some implications of this change in responsibility: 1. Responsible domains using SSP delegation will not be able to change signing providers (delegatees) without forfeiting any positive reputation they have accumulated. It should really be the delegator's positive reputation, because they are the ones acting responsibly in their mailing practices and/or the use of outside mailing providers. It should not be necessary to start over if you change ISPs or outbound marketing providers. 2. Delegators are more likely to be diligent in the choice of delegatees when it is their own reputation at stake. When it is the delegatee's reputation at stake, they can always employ an unreliable party, or in the extreme a spammer, and when abuse is reported simply say "oh, sorry" but not endure any impact on their reputation at all. 3. We are already aware of the potential for the use of throw-away domain names by bad actors who otherwise might accrue a bad reputation. This opens a new possibility: it isn't necessary to get a new domain, just delegate signing to a new entity and "all is forgiven". -Jim _______________________________________________ NOTE WELL: This list operates according to http://mipassoc.org/dkim/ietf-list-rules.html
