Keyzero.org: The root public key repository
Keyzero.org is the fallback DEA (Domain Email Authority) for non-keymail systems until they acquire their own DEAs. For example, any email ID can deposit its public key in keyzero.org and receive encrypted email using that public key. If an email's domain has its own DEA, then the public key in its own DEA will override the key in keyzero.org.
An email ID can register its public key with keyzero.org by sending
the public key in the body of an email from that email ID to dea@dea.