Mass Mail criteria issue

Team,
I try to set a criteria as:
State Contains New Delhi,Gurgaon,Noida
This returns 1016 Leads

But when I set criteria as:
State Contains New Delhi,Gurgaon,Noida
AND
Email doesNOT contain @abc.com
This returns 10,000+ leads

Actually it should be equal to or less than 1016 leads

Please analyse this issue or let me know if I am doing anything different!!!

Thanks,
Shan
sales

lshankar