optimize tables for search using LIKE clause in MySQL

Question

I am building a search feature for the messages part of my site, and have a messages database with a little over 9,000,000 rows, and and index on the sender,

Answer 1

select * from emp where ename like '%e';

gives emp_name that ends with letter e.

select * from emp where ename like 'A%';

gives emp_name that begins with letter a.

select * from emp where ename like '_a%';

gives emp_name in which second letter is a.