Serving targeted promo codes in Facebook ads

I am working on a solution which is to service preassigned unique promo codes to customers across multiple channels.

  1. Customer receives an email with a unique promo code, which at the time of send is assigned to his email address
  2. This is stored within our CRM system, and can be provided in a combination of this customer’s hashed email address (HEM).
  3. Same promo code we want to present in a Facebook ad, which is targeted to same individual

I know a list of unique promo codes can be uploaded to Facebook, for use with offer ads, but there is nothing which indicates whether this upload can be pre-mapped to an email address or HEM.

Another solution, which I consider pursuing, is to allow the ad to make use of a dynamic feed which would take a unique identifier (HEM?) as a parameter, and return the assigned promo code, which the ad would parse and present. However so far I have only been able to identify product feed as the only option of serving feed based dynamic content to FB ads.

Any advice will be much appreciated.
Thank you

Best regards

Lukas