Email Content

I would like to send EMAIL with the custom body msg using the following code. 

function generateOTP() {
var digits = '0123456789';
let OTP = '';
for (let i = 0; i < 6; i++ ) {
OTP += digits[Math.floor(Math.random() * 10)];
}
return OTP;
}
document.write("Dear customer, your OTP for registration is "+generateOTP()+". Use this code to validate your login.")

The code generates the random OTP number.


How can I send using email tools in the form builder?