1. A method, comprising: identifying an image that was provided as an attachment in an e-mail message; performing an optical character recognition (OCR) procedure on textual data included in the image; determining whether the image includes predetermined data by comparing a portion of the image to a portion of the predetermined data; and performing an action based on the determination, wherein the action includes quarantining the image and preventing a subsequent e-mail message, which attaches the image, from propagating in a network based on identifying the portion of the image as being associated with confidential information.