At the most recent Meeting of the Moodle Community Austria I had the idea to create a plugin which provides the opportunity to import attachments from e-Mails. This can be an advantage if you want to upload files from tablets like iPads or if it is not possible to install other repository plugins.
Until now there existed many other repository plugins like Dropbox or FTP which either need an appropriate infrastructure within your organization (access to ftp / webdav sources) or force the users to do some configuration steps. This can be a barrier for some organizations or users.
The main advantage of using the email repository is that you can use nearly every mailbox that provides access via imap or pop, which is rather easy. Any user can send an email to this address e.g. email@example.com or firstname.lastname@example.org. As long as the senders mail-address is the same as the mail-address of the moodle-user the user can import the attachment into moodle.
On the configuration page of the moodle plugin there is a parameter to specify after how many days old emails should be deleted.
The e-Mail Repository Plugin is distributed under GPL 3 on github –> https://github.com/rschrenk/moodle_email_repository
Have fun using it!