OTP-send-email.html

%%[
IF RequestParameter("submitted") == true THEN

/* generate an OPT */

set @num1 = 1000
set @num2 = 9999
set @OTP  = random(@num1, @num2)
        
/* send a triggered email containing the opt */

SET @ts = CreateObject("TriggeredSend")
SET @tsDef = CreateObject("TriggeredSendDefinition")
SET @ts_extkey = "43099" /* replace with ID of your Triggered Send */
SET @ts_email = RequestParameter("email")

SetObjectProperty(@tsDef, "CustomerKey", @ts_extkey)
SetObjectProperty(@ts, "TriggeredSendDefinition", @tsDef)
 
SET @ts_sub = CreateObject("Subscriber")
SetObjectProperty(@ts_sub, "EmailAddress", @ts_email)
SetObjectProperty(@ts_sub, "SubscriberKey", @ts_email)

SET @attr = CreateObject("Attribute")
SetObjectProperty(@attr, "Name", "OTP")
SetObjectProperty(@attr, "Value", @OTP)
AddObjectArrayItem(@ts_sub, "Attributes", @attr)

AddObjectArrayItem(@ts, "Subscribers", @ts_sub)

SET @ts_statusCode = InvokeCreate(@ts, @ts_statusMsg, @errorCode)

/* display a form where subscriber submits otp */
]%% 

<form action="%%=RequestParameter('PAGEURL')=%%" method="post">
<label>OTP: </label><input type="text" name="OTP" required=""><br>  
<input name="email" type="hidden" value="%%=RequestParameter("email")=%%"><br>  
<input name="submittedOTP" type="hidden" value="true"><br>
<input type="submit" value="Submit">
</form>