check if any entry in list older than 7 days, delete second double entry

Hi,

I am having a sheet where I keep track of when online surveys have been sent to users. The users enail address (column K) may be on the list for several times, but I need to make sure that there is at least a 7 days pause between sending the first mail and the second, depending on the visit date (column G).
If there are less than 7 days between two entries with the same email address, the user is not qualified for taking another survey.

I was thinking to write an IF formula which returns either 1 or 0 and then let conditional formatting highlight and HIDE the row via a VBA loop, but I am open for any sort of suggestions as I am not sure how to start with this formula.

Any help is much appreciated.


Thanks,
A2k

sample 20130911.xlsx


EDIT: Added attachment, thanks.