Designated Mailers Protocol

Drawbacks Compared to Other Proposals

• More individual records in DNS zone
• Wildcard DNS records help but are not required
• More work for the domain administrator
• Automated tools can reduce this impact
• More work up front reduces network bandwidth and processing time


• No easy way to designate another domain's networks
• Duplication of records for multiple domains
• Extensions to DMP may address this at the cost of more DNS queries


• Overloads a DNS record type defined for other purposes
• Again, existing documents (RFC 1464) support this usage
• A new record type will not change the network usage or event path, so DMP could work with a new record type
• Not all DNS servers transparently support undefined record types


• Arbitrarily defines a name space ("_smtp-client")
• Special name space may not be required or may be changed
• Underscores are allowed for non-hostname DNS records (ie: RFC 2782, DNS SRV) and avoid confusion with hostnames