So the mail protocol never considered any type of authentication.

FORBES: Authenticate This!

The law-enforcement official said all of the mayor's mail is sorted and handled in several off-site facilities, and mail sent to the mayor's home goes through the same screening protocol.

WSJ: Letters to Mayor Bloomberg Tested Positive for Ricin

"Even with the new normal of being informal, the proper way to start an e-mail is with 'Dear, '" said Cynthia Lett, director of the Lett Group, a protocol training company in Silver Spring, Maryland.

CNN: Is 'Dear' dead?