Match Audience Rules to See Experiences: Sometimes you want to confirm that your audience matching works. Other times you just want to check the look and feel of the activity. If this setting is toggled to the "on" position, testers must meet targeting requirements to qualify to see the experiences. For Experience Targeting (XT) activities, a single activity URL is provided. The experience you see is determined by you qualifying for one of the targeting rules.
If this setting is toggled to the "off" position, clicking the links show you the experiences regardless of whether you qualify or not. When performing QA, you can switch back and forth between requiring or not requiring that audience targeting is respected
Using the QA link without this setting would lead to qualifying for the experience every single time the link is accessed.
I've looked over this a few times. I think you are saying that you are that you are not able to enter the activity based on the mbox parameter you are targeting and you have verified that the parameter is passing. If that is the case here are some other possible reasons why you might not be entering the activity.
1. Not qualifying for another part of the audience rules.
2. Not qualifying based on the URL or URL parameter this activity was configured for.
3. Not getting into the expected experience instead you may be entering a different experience.
If you have ruled out all of the above I would say it's time to open a ticket with support email@example.com
Mihnea Docea | Technical Support Rep, Customer Care | Customer & Employee Experience | Adobe | (:: 1 (800) 497-0335