Table schema:
CREATE TABLE customers (customer_name VARCHAR, customer_id VARCHAR); CREATE TABLE mailshot_customers (customer_id VARCHAR)

Question: Show the names of customers who have the most mailshots.
SQL: SELECT T2.customer_name FROM mailshot_customers AS T1 JOIN customers AS T2 ON T1.customer_id = T2.customer_id GROUP BY T1.customer_id ORDER BY COUNT(*) DESC LIMIT 1