When you buy an extension pack and tick'redeem automatically' you get the following message:

Your game codes have been sent to your e-mail address and should arrive shortly. You can redeem your codes and add them to your account any time you like here. You can track your purchases and redeemed codes on your Account status page or use it as a reference if any questions arise.

which is incorrect. The email says:

Your purchase of the following item(s) was successful:

- Upgrade Kit Zero: 1 * 9.99 EUR
- Upgrade Kit One: 1 * 9.99 EUR

The purchased items have been automatically redeemed to your account.

which is correct.