IF Condition in an SQL query

Question

I\'m a newbie to SQL Server. Please help me to write the following Logic in a query.

If getnow() > today 4 PM
Then
    SELECT *
    FROM table
    WHERE M         


        

Answer 1

select *
from table
where DATEDIFF(day, GETDATE(), maildate) = case when
    DATEPART(hour, GETDATE()) >= 16 then 1 else 0
end