function validEmail(email){invalidChars=" /:,;"
if(email==""){return false;}
for(i=0;i<invalidChars.length;i++){badChar=invalidChars.charAt(i)
if(email.indexOf(badChar,0)!=-1){return false;}}
atPos=email.indexOf("@",1)
if(atPos==-1){return false;}
if(email.indexOf("@",atPos+1)!=-1){return false;}
periodPos=email.indexOf(".",atPos)
if(periodPos==-1){return false;}
if(periodPos+3>email.length){return false;}
return true;}