If you are using one of Optimove's native channels (OptiMail, OptiMobile, OptiText, and more), you should use Optimove's Manage Templates to build a template containing the promo code as a personalization tag. There are two options for setting this up:
Generic Promo Code
The promo code is generic for each campaign, meaning that all customers in the same campaign will be assigned the same promo code.
In this case, from the General category, use the PROMO tag, as seen in the image below:
Personalized Promo Code
This option should be used when each customer receives a unique promo code. In this case, from the General category, use the UNIQUE_PROMO tag, as shown in the image below:
Please note:
If this attribute is not available as a Personalization tag in your Optimove instance, ask your CSM to create the "promo code" attribute for you.