From the ATF site;
Page 67;
http://permanent.access.gpo.gov/lps41631/2005/p53004.pdf"The purchase or other
acquisition of a firearm shall, except as
provided in paragraph (g) of this section,
be recorded not later than the close of the
next business day following the date of
such purchase or acquisition.
The record
shall show the date of receipt, the name
and address or the name and license
number of the person from whom received,
the name of the manufacturer and
importer (if any), the model, serial number,
type, and the caliber or gauge of the firearm"
A DL may be a handy way to do it but it is not required,just name a adress, in transaction Phillip is involved in,especially as a "claw back" requirment after the deal was done.
For a in person sale with a 4473,yes a DL would be the way to do it but for guns recieved through the mail it is not required nor does it offer any protection IMO.If it where me,and I was unlicensed I would just call the guy and see what and why he wants it,perhaps it could be straightend out over the phone when both parties understand what the other wants.