I'm in the process of setting up a new client in CM and ran into a new question that I want to ensure I answered correctly.
It appears Campaign Monitor uses the "cm" namespace for its DomainKeys-Signature header (s=cm;). Is there a central registry to ensure that there aren't any namespace collisions/conflicts? Our client uses a few different mail providers and their sysadmin is concerned about conflicting headers.
Any info would be much appreciated.
The short answer is no, there isn't a registry of these namespaces, but the chances of there being an overlap for any particular system have got to be very, very low.
We've certainly never heard of any problems like that.