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 MailDate is Tomorrow
Else
    SELECT *
    FROM table
    WHERE MailDate is Today

Answer 1

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

Answer 2

IF datepart(hh, getdate()) >= 16
    BEGIN
        SELECT *
        FROM table
        WHERE DateDiff(day, getdate(), MailDate) = 1
    END
ELSE
    BEGIN
        SELECT *
        FROM table
        WHERE DateDiff(day, getdate(), MailDate) = 0
    END