As far as i get it, if you operate within same directory, the operation of 'sending those files' will change the atime again.
So next iteration of code will detected those again as accessed in the last 10 minutes (10 minutes or less).
This could be mitigated by issuing
touch -at <TIMESTAMP> files to change all files sent 20 minutes behind script execution time.
This will, of course, fake atime on processed files.
As for
-newer i'm not sure it will operate on atime or ?
Perhaps some awk parsing and
ls -lutr... shouldn't be to big.
I'll get back to you on that when i get to hpux box these days
Regards
Peasant