The present invention is directed to a method and system for compressing attachments to electronic mail communications for transmission. In an e-mail communications system, a table stores, for each of a plurality of different types of files, a compressibility value corresponding to a percentage by which the file can be compressed in size. An e-mail attachment configuration module is configured to compress each attachment file of a type having a compressibility value greater than a threshold value in an e-mail communication. In another embodiment, the e-mail attachment configuration module compresses a number of the plurality of attachment files according to file size and the corresponding compressibility value, such that the total size of the e-mail communication after compression is maximized and is less than a threshold size. The attachment configuration module can be incorporated into a system for configuring packages of application files, designated from within user applications, to be sent as e-mail attachments in e-mail communications.