How to improve the usability of WKD even further (advanced features)
This is an extension of the basic features to improve the usability of WKD.
Offer WKD in signature area
Email clients should offer WKD there where users can see and check the signature of an email. When the need is there to validate a signature it seems obvious to look on a keyserver for the key with the specific ID. Even so there may be cases when the sender of the email did only upload a key to a WKD server and not to a keyserver. Then it makes sense to also involve WKD servers in the lookup.
Nonetheless, clients should not fetch keys automatically because this behavior could leak information to spammers.
Displays basic trust (Signature)
Clients should distinguish between keys without any information about their trust and keys fetched via WKD that have at least a basic trust (See the explanations of the web key directory concept why). It displays this trust in the area to check the signature of an email.