webook - is it possible to assign a value to an attribute during the send/receive data step?

The use case is:

I want to create a personalised promocode that is a random generated number during the campaign and send it through email

I am doing this:

1. Create the webhook step. In the request I create the random number (promocode)
2. In the response I receive a confirmation (I just receive 200 OK, not the promocode)
3. I want to send the promocode through an email on the same campaign

I got stuck because I can/know to store the generated promocode and then retrieve it during the email step. I tried to assign a profile attribute during the request, but I couldn’t. I tried use the response attributes, but the variable used in the request is not there. 

Please help :)