The bank I work at currently accepts ARP issue files to be sent to us via encrypted email. In the beginning we purchased PGP to handle the encryption and one of the clerks in out deposit operations department would receive an email with an encrypted attachment which she would decrypt, save to disk, and then upload to our mainframe for processing. Over a short period of time the number of customers opting to send us email attachments grew faster than we anticipated, and so I developed a Python application to automatically fetch the emails from an IMAP mailbox, decrypt any attachments, and save them to a directory for upload to the mainframe at a later time. There is also a piece to this that periodically searches a download directory for files to encrypt and send out.
Currently this program is usable, but is highly customised for our specific environment. I would like to make this product more generic so that it will run on other platforms (yes, it is customised for our Windows environment at the moment) and to be used for other industried (it should eventually be useful to anyone who needs to automate regularly sending and/or receiving encrypted information through email.) It also uses GPG to encrypt and decrypt, and I would like to incorporate the encryption functionality into the program itself.