how to get index scan at work?

Hi folks, <p>can any one help me with this. <p><tt><font color="#000099">tradein_clients=> explain SELECT  
email_idfrom email_bank where lower(email) = 'mallah@grex.org' ;</font></tt><br /><tt><font color="#000099">NOTICE: 
QUERYPLAN:</font></tt><tt><font color="#000099"></font></tt><p><tt><font color="#000099">Seq Scan on email_bank 
(cost=0.00..25223.02rows=9385 width=4)</font></tt><tt><font color="#000099"></font></tt><p><tt><font
color="#000099">EXPLAIN</font></tt><br/><tt><font color="#000099">tradein_clients=> explain SELECT   email_id from
email_bankwhere email = 'mallah@grex.org' ;</font></tt><br /><tt><font color="#000099">NOTICE:  QUERY
PLAN:</font></tt><tt><fontcolor="#000099"></font></tt><p><tt><font color="#000099">Index Scan using
email_bank_email_keyon email_bank  (cost=0.00..4.83 rows=1 width=4)</font></tt><tt><font
color="#000099"></font></tt><p><tt><fontcolor="#000099">EXPLAIN</font></tt><tt></tt><p>i want to query the data in case
insensetivemanner , but if i put lower(email) <br />index is not being used  any workarounds?? <br />  <p>regds <br
/>Mallah.<br />  <br />  <br />