function isEmailValid (email) {
if (email.length<5) {return false};
space_location = email.indexOf (" ");
at_location = email.indexOf ("@");
dot_location =  email.indexOf (".");
if (at_location == -1 || dot_location == -1 || space_location == 1) {return false};
//if (at_location > dot_location) {return false};
if (at_location == 0) {return false};
//if (dot_location - at_location < 2) {return false};
if (email.length - dot_location < 2) {return false};
return true;
}