Systems, devices, and methods are provided for enabling a user to control the content of text-based messages sent to or received from an administered device. In some embodiments, a message will be blocked (incoming or outgoing) if the message includes forbidden content. In other embodiments, the objectionable content is removed from the message prior to transmission or as part of the receiving process. The content of such a message is controlled by filtering the message based on defined criteria. The criteria may be defined according to a parental control application. These techniques also may be used, in accordance with instructional embodiments, to require the administered devices to include certain text in messages. These embodiments might, for example, require that a certain number of Spanish words per day be included in e-mails for a child learning Spanish.