Verizon Deploys 'Certified Email' > So what do the customers get?

said by jester121:

Mebbe so, but it's also trivially easy for the filtering system to strip the header when it deposits the message into your mailbox (after the scanning is done, but before you see it).

said by Rob:

If that's the case, then spammers can just add that "mark" to their own headers, hence bypassing the filters!