There are 3 possible scenarios here;
 1. They are trying to drop you a virus in document.zip which apparently contains a .pdf file. DO NOT open it, upload it here http://www.virustotal.com/
          Let us know if it has any results or not.
 2. They are attempting to phish you, hoping that you will initiate contact with them so they can gather info from you.

 3. They are just using your email as input while attempting to place bogus tranfers.


 I did not look these guys up, 13450 Sunrise Valley Drive, Suite 100 Herndon, VA 20171 (703)561-1100 2011 NACHA - The Electronic Payment Association
  Is this company at all familiar to you?


Also, if you can manage to copy the email header that would be helpful. If you are not sure how let us know what email client you are using, i.e hotmail, gmail, outlook or whichever  and I am sure someone can point you to where to do so.