First big question that how we can change the email address in Magento 1.8 after lots of finding I got the solution so for that I share with you guys.

Open Putty with your default Username & Copy – Paste the below Script in it.

Customer Email change

select * from sales_flat_order_address where email='old@gmail';
update sales_flat_order_address set email='new@gmail.com' where email='old@gmail' and telephone='Telephone Number';

select * from customer_entity where email = 'old@gmail';
update customer_entity set email = 'new@gmail.com' where email ='old@gmail';

select * from sales_flat_order where customer_email='old@gmail';
update sales_flat_order set customer_email='new@gmail.com' where customer_email='old@gmail';

select * from sales_flat_quote where customer_email = 'old@gmail';
update sales_flat_quote set customer_email='new@gmail.com' where customer_email='old@gmail