You may have a hard time arguing they meant to require an email address, but at the same time, stuff sent there would not be valid.
From Google's old DMCA page[1] (cached 13 April 2013 - now directs to an automated system):
> To file a notice of infringement with us, you must provide a written communication (by fax or regular mail and not by email, except by prior agreement)
From Google's current support pages [2]:
> Send the written communication to the following address: <postal address> OR fax to: <fax number>
> To file a counter notification with us, you must provide a written communication (by fax or regular mail -- not by email, except by prior agreement)
[1] http://www.google.co.uk/dmca.html [2] http://support.google.com/bin/answer.py?hl=en&answer=112...
I'd say you have a reasonable argument either way, my point was more on the side of "A judge may disagree".
Hence "you may have a hard time arguing".