Double-click the Query activity.
Click the Edit query link and select the recipients you want to target.
Link the Query activity to the Split activity.
This activity lets you create several populations: the one that receives delivery A, the one that receives delivery B, and the remaining population. Using random selection lets you target just part of the population of each delivery.
Creating population A:
Double-click the Split activity.
In the existing tab, change the label to population A.
Select the Limit the selected records option.
Click the Edit link, select Activate random sampling, and click Next.
Set the threshold to 10%, then click Finish.
Creating population B:
Click Add to create a new tab for population B.
Limit the population to 10% as previously.
Creating the remaining population:
Go to the General tab.
Select Generate complement.
Change the label to specify that this population includes neither A nor B, and click OK to close the activity.
You can now create the two delivery templates (see Step 3: Create two delivery templates).