The product images shown in email recommendations are pulled from the product feed that is sent to Episerver Personalization.
There are two ways to adjust the image sizes:
1) The most robust and recommended way is to add the appropriate HTML and CSS in the email template to adjust the size of the recommendation images. Please contact your Email Service Provider if you are unsure how you can update your templates.
2) If you are able to provide Episerver with image links for the images in the correct size, then they can be used in email recommendations. You can either adjust the image links directly in your product feed or add a product attribute in the feed with the alternative links, which Episerver can configure to be used in email recommendations.
Please note that if you edit the main image links in the product feed, this may also affect the product images which are used for on-site recommendations (if you use the Perform product).
Contact the firstname.lastname@example.org if you would like to discuss the possible options in more details.