1. A computer-implemented messaging system, comprising: a computing device using an untrusted message service for sending a message to one or more recipients, wherein a rules component associated with the untrusted message service provides rules to a client device and is configured to supply one or more of modified rules and new rules to the client device to generate a security template; wherein the security template allows exposure of a header portion and a subject portion of the message at the untrusted message service; wherein the security template further prevents a body portion and message attachments of the message from being exposed at the untrusted message service; and wherein the security template is configured to be applied by the client device in response to a determination that the untrusted message service is being used to send the message, wherein applying the security template includes attaching one or more attributes of the security to the message.