A system and method for controlling message attachment handling functions on a mobile device is described herein. An attachment handling control can be set to identify one of a number of selected attachment handling control modes. Depending on the attachment handling control mode identified, a request for the attachment structure that includes a decrypted session key for an encrypted message received at the mobile device may or may not be automatically sent to a remote server. This may provide the user with increased control over the content of an encrypted message that the remote server may access when determining the attachment structure for a message.