iTunes stores personal information (including iTunes account email and name) in your music files, even when they are DRM-free. This isn’t normally a problem, but some of us simply don’t like having such personal info in places it shouldn’t be; or if you are victim to malware/attack, then you might find your music inadvertently floating about on the web. Whatever be your reason, there are ways to remove the personal information.
You can verify if any of your AAC files have personal info by right-clicking on it in iTunes and going to the “Summary” tab.
One way, if you do not have many tracks, is to simply tell iTunes to do it. There are lots of sites explaining how to do this, such as This Site.
However, this approach is a pain (you have to delete the old tracks after), and error prone (you might forget some). Another way is to use Atomic Parseley, a command line tool that can edit file meta information:
I confirmed this worked, but it is still not automatic. Someone needs to create a simple tool that scans a directory hierarchy and checks for the existence of personal info, and if present, prompts the user if they want to delete it. Maybe i’ll get to that someday.
Another option is to the the application The Tagger, which although not free, has a “remove personal info” menu option for purging your files. Unfortunately, this option does not work on directories, so you must manually navigate into each one and execute the command. I also confirmed this to work.
It also seems you can use MP4Box and with some command line magic, purge the information that way: