Preventing spam messages

A method for blocking unwanted messages sent to a mobile device is provided. In one embodiment, messages received when the MDN is deactivated are responded to with a message asking the sender to delete the MDN from the sender's distribution list. In another embodiment, messages are received with a subscription date. The subscription date is compared to the most recent provisioning date of the MDN. If the provisioning date is after the subscription date, then the message is blocked and a reply message may be generated indicating to the sender that the MDN should be removed from the sender's distribution list.