I just noticed the week count.  was coming back to edit...

I think this logic is close, but the flaw that I spot is that if you have a 20 day span, this code only checks the FIRST and LAST day...

I noticed this thread because of the news letter! 

delete

FROM         Customer

WHERE     (autoid >

                          (SELECT     MIN(autoid)

                            FROM          Customer t1

                            WHERE      Customer.email = t1.email))