In order to save attached files, you just need to modify ~/.procmailrc file to read something like:
# First Recipe
* ^Content-Disposition: attachment;
| munpack -q -C /WHERE/TO/SAVE
# Second Recipe
The first recipe will filter out those mails from SOMEBODY with attachment(s) and save the file(s) to /WHERE/TO/SAVE folder. Make sure that you have mpack installed on the system:
$ sudo apt-get install -y mpack
The second recipe will simply discard all messages afterward. Therefore, nothing but the attachments will be saved locally.