1. A method for filtering messages on mobile devices, the method comprising: receiving messages addressed to a user; evaluating a message from the messages to determine whether the message is desirable; providing desirable messages from the one or more messages to a mobile device associated with the user, desirability of the messages having been determined based on urgency or time-sensitivity of the messages; wherein, undesirable messages from the messages are less urgent or less time-sensitive than the desirable messages and are withheld from delivery to the mobile device or hidden from view on the mobile device until requested for viewing by the user; wherein the desirable messages further include messages with a subject line including a key word present in a subject line of a previously outgoing message sent by the user.