I use the upload@mypogoplug all the time. 

I created a folder on my pogoplug called fileuploadbyemail. I use this folder to keep track of the stuff  I've uploaded to the pogoplug by email forward. I then have to login to the web interface or go to the folders to move the files to the different directories they should go in.

It would work like this.

1. send email to upload@mypogoplug.com

2. In the subject line: put the following command Folder: paystubs 

Result: So in this scenario. When I send my paystubs to upload@mypogoplug.com. When the file gets to the pogoplug, the software would look at the subject and copy it to the paystubs directory.

Gmail does this with labels.