function checkData (){

if (document.f.Email.value.length ==0){
document.f.Email.focus();
alert("Please enter an e-mail address.");
return false;
}
if (document.f.Email.value.length >0){
i=document.f.Email.value.indexOf("@")
j=document.f.Email.value.indexOf(".",i)
k=document.f.Email.value.indexOf(",")
kk=document.f.Email.value.indexOf(" ")
jj=document.f.Email.value.lastIndexOf(".")+1
len=document.f.Email.value.length
if ((i>0) && (j>(1+1)) && (k==-1) && (kk==-1) && (len-jj >=2) && (len-jj<=3)) {
} else {
document.f.Email.focus()
document.f.Email.select()
alert("Please enter a valid email address.")
return false
}
}
}