This javascript will help you to validate the email-id given in a form field.
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<script type="text/javascript">
function checkMailId(mailids)
{
var arr = new Array('.com','.net','.org','.biz','.coop','.info','.museum','.name','.pro'
,'.edu','.gov','.int','.mil','.ac','.ad','.ae','.af','.ag','.ai','.al',
'.am','.an','.ao','.aq','.ar','.as','.at','.au','.aw','.az','.ba','.bb',
'.bd','.be','.bf','.bg','.bh','.bi','.bj','.bm','.bn','.bo','.br','.bs',
'.bt','.bv','.bw','.by','.bz','.ca','.cc','.cd','.cf','.cg','.ch','.ci',
'.ck','.cl','.cm','.cn','.co','.cr','.cu','.cv','.cx','.cy','.cz','.de',
'.dj','.dk','.dm','.do','.dz','.ec','.ee','.eg','.eh','.er','.es','.et',
'.fi','.fj','.fk','.fm','.fo','.fr','.ga','.gd','.ge','.gf','.gg','.gh',
'.gi','.gl','.gm','.gn','.gp','.gq','.gr','.gs','.gt','.gu','.gv','.gy',
'.hk','.hm','.hn','.hr','.ht','.hu','.id','.ie','.il','.im','.in','.io',
'.iq','.ir','.is','.it','.je','.jm','.jo','.jp','.ke','.kg','.kh','.ki',
'.km','.kn','.kp','.kr','.kw','.ky','.kz','.la','.lb','.lc','.li','.lk',
'.lr','.ls','.lt','.lu','.lv','.ly','.ma','.mc','.md','.mg','.mh','.mk',
'.ml','.mm','.mn','.mo','.mp','.mq','.mr','.ms','.mt','.mu','.mv','.mw',
'.mx','.my','.mz','.na','.nc','.ne','.nf','.ng','.ni','.nl','.no','.np',
'.nr','.nu','.nz','.om','.pa','.pe','.pf','.pg','.ph','.pk','.pl','.pm',
'.pn','.pr','.ps','.pt','.pw','.py','.qa','.re','.ro','.rw','.ru','.sa',
'.sb','.sc','.sd','.se','.sg','.sh','.si','.sj','.sk','.sl','.sm','.sn',
'.so','.sr','.st','.sv','.sy','.sz','.tc','.td','.tf','.tg','.th','.tj',
'.tk','.tm','.tn','.to','.tp','.tr','.tt','.tv','.tw','.tz','.ua','.ug',
'.uk','.um','.us','.uy','.uz','.va','.vc','.ve','.vg','.vi','.vn','.vu',
'.ws','.wf','.ye','.yt','.yu','.za','.zm','.zw');
var mai = mailids;
var val = true;
var beforeat="";
var afterat="";
var afterat2="";
var dot=mai.lastIndexOf(".");
var con=mai.substring(dot, mai.length);
con=con.toLowerCase();
con=con.toString();
for(var i=0;i<(arr.length);i++)
{if(con == arr[i]){val=true;break;}else{val=false;}
}
var att=mai.lastIndexOf("@");
beforeat=mai.substring(0,att);
beforeat=beforeat.toLowerCase();
beforeat=beforeat.toString();
var asci1=beforeat.charCodeAt(0);
afterat=mai.substring(att+1, dot);
afterat=afterat.toLowerCase();
afterat=afterat.toString();
afterat2=mai.substring(att+1, mai.length);
afterat2=afterat2.toLowerCase();
afterat2=afterat2.toString();
if(beforeat=="" || afterat=="" || beforeat.length>30)val=false;
if(afterat2.length>64 || afterat.length<2)val=false;
if((afterat.charCodeAt(0))==45 || (afterat.charCodeAt(afterat.length-1))==45)val=false;
if(val==true)
{if(asci1 > 47 && asci1 < 58)val=false;if(asci1 < 48 || asci1 > 57){for(var i=0; i<=beforeat.length-1; i++){var asci2=beforeat.charCodeAt(i);if((asci2<=44 || asci2==47) || (asci2>=58 && asci2<=94) || (asci2==96) || (asci2>=123 && asci2<=127)){val=false;break;}}for(var j=0; j<=afterat.length-1; j++){var asci3=afterat.charCodeAt(j);if((asci3<=44) || (asci3==46) || (asci3==47) || (asci3>=58 && asci3<=96) || (asci3>=123 && asci3<=127)){val=false;break;}}
}
}
if(val==false)
{alert("Your maild "+mai+" is not valid");return false;
}
else
{return true;
}
}
</script>
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