GO to DHL Worldwide Express website
http://www.dhl.comSelect USA
A new page will open
At the top highlight tracking and click on TRACK BY REFERENCE
In the Reference field type CORRESPONDENCE
For the Shipment date you should select a day before and after the date NVC said they sent your file.
Customer number leave blank
Origin Postal code should be 03801
Then Click Track (thanks to YuAndDan and to Randy)