One way:
<b>Extract</b><br /><br /><table border="1" cellspacing="0" cellpadding="0" style="font-family:Arial,Arial; font-size:8pt; background-color:#ffffff; padding-left:2pt; padding-right:2pt; "> <colgroup><col style="font-weight:bold; width:30px; " /><col style="width:217px;" /><col style="width:87px;" /></colgroup><tr style="background-color:#cacaca; text-align:center; font-weight:bold; font-size:8pt; "><td > </td><td >A</td><td >B</td></tr><tr style="height:21px ;" ><td style="font-size:8pt; background-color:#cacaca; text-align:center; " >1</td><td style="font-size:10pt; ">amit.dhamija@rediffmail.com</td><td style="font-size:10pt; ">rediffmail</td></tr></table><br /><table style="font-family:Arial; font-size:10pt; border-style: groove ;border-color:#00ff00;background-color:#fffcf9; color:#000000; "><tr><td ><b>Spreadsheet Formulas</b></td></tr><tr><td ><table border = "1" cellspacing="0" cellpadding="2" style="font-family:Arial; font-size:9pt;"><tr style="background-color:#cacaca; font-size:10pt;"><td >Cell</td><td >Formula</td></tr><tr><td >B1</td><td >=REPLACE(LEFT<span style=' color:008000; '>(A1,FIND<span style=' color:#0000ff; '>(".",A1,FIND<span style=' color:#ff0000; '>("@",A1)</span>)</span>-1)</span>,1,FIND<span style=' color:008000; '>("@",A1)</span>,"")</td></tr></table></td></tr></table>