Activity Pointer Table
The Activity Pointer table contains the email content held by D365 in the dataverse. Although Microsoft store (and charge for) attachments in a different location, any embedded images (typically in-line images like company logos, or social media links) are stored as data.
Data is at a premium, and in the case of email tracking is often the reason that the Activity Pointer table becomes so large within D365 organisations.
Data Reduction
As the data held in the emails is repeated, those clever engineers at D365 Shrinky allow you to extract a single version of the image, and then present it back (seamlessly) to the user when the email is shown in D365. No change in behaviour or functionality.
The emails look the same, have the same images in, but using D365 Shrinky, you have saved storage against all the instances of that image in your database.
D365 Shrinky
Remove Repeated Embedded D365 Email images stored as data