Method, device, and computer program product are provided for differentiated treatment of incoming and outgoing emails based on a network server. A server receives a query from a gateway, and the query includes information about an email received by the gateway. The server obtains rules for processing the email of the query. The server determines an identity for the email based on the rules for processing the email. The server transmits the identity to the gateway to cause the gateway to send the email having the identity to a post office server. The email having the identity is configured to cause the post office server to process the email based on the identity.