Using a targeted subject line allows you to make your content look like it is tailored to the individual subscriber.This feature allows you to specifically send a smaller more defined list of the larger list a different subject line. As long as the subscribers in the smaller list, also exist within the larger list, you can specify that you want all the females to receive a more specific subject line tailored to them.
In the Mailing Designer, navigate to the Test tab.
Click Targeted Subject Line.
Here you can view the Subject, Target Group Name and Count.
This confirms the subject lines you are testing, to whom you are sending them, and how many people you can expect to receive each version.
Using a targeted subject line is a great way to increase your open rate!