How to create a Data Extension with the contacts that were excluded from a send?

Engage provides a dashboard where you can see for each Send that was done which contacts were included and excluded.

This data remains available for 6 months after the Send.

If you want to have a Data Extension containing the contacts that were excluded from a Send, you can do the following:

1. Add a new field to the source Data Extension which contains the contacts that should receive the send. The field should be a boolean, which we will be setting to true for excluded contacts. You can call it something like Excluded, but there is no strict requirement for this field name.
   Optionally, you can set the default value to False.
2. In Journey Builder, on the Excluded path, add an Update Contact activity. 
   1. As the Data Extension, select the source Data Extension to which we've added the boolean field. This Data Extension should also be the Entry Source of this Journey.
   2. As the Attribute Value, set the boolean field (in our case named Excluded) to True.

As contacts go through the Excluded path of the DESelect Engage component, their record will be updated in the source data extension, the Excluded field will be set to true.