Nice, I did not know this. Cool stuff Madhi Sr.

Very interesting technique madhivanan. Here is an XML version.

declare @t table(email varchar(100))
insert into @t 
select 'test@yahoo.com' union all
select 'test@msn.com' union all
select 'test@gmail.com' union all
select 'test1@yahoo.com' union all
select 'test@sify.com' union all
select 'test2@yahoo.com' union all
select 'test3@msn.com' union all
select '' union all
select null union all
select 'test1@gmail.com' 

;WITH cte AS (
    SELECT CAST(
    	'<i>' + REPLACE(email, '@', '</i><i>') + '</i>'
    	AS XML).value('/i[2]', 'varchar(50)') AS Domain
    FROM @t 
)
SELECT
    Domain, 
    COUNT(*) AS Cnt
FROM cte
WHERE Domain IS NOT NULL
GROUP BY Domain 
ORDER BY COUNT(*) DESC

/*
Domain                                             Cnt
-------------------------------------------------- -----------
yahoo.com                                          3
gmail.com                                          2
msn.com                                            2
sify.com                                           1
*/

Another method is

select 
    substring(email,charindex('@',email)+1,len(email)) as domain,
    count(*) as emailcount 
from 
    @t
where
    email>''
group by
    substring(email,charindex('@',email)+1,len(email))
order by
    emailcount desc

Hi.. How stuff function works? Can u please explain?

Man, this is worth a big blog post! Loved the subject.

rajbluesea, Stuff function is used to replace certains characters to other characters. In this case it finds the position of the character @, then replaces all characters from first character to @ by empty string. So you will have only domain name