When the setting "No Re-entry" is chosen, is this based on Subscriber Key? Meaning, if a subscriber with Subscriber Key "email@example.com" and Email Address "firstname.lastname@example.org" gets injected into the journey, then say a week later, they change their email address to be something like "email@example.com" (while SubscriberKey remains the same, "firstname.lastname@example.org"), can this subscriber enter the journey again if "No Re-entry" is selected, or will they not be able to because it's based off of SubscriberKey?
If I remember correctly it's based off of Contact ID but if your contact's email address changes they should still be prevented from entering as long as their Contact ID remains the same.
When I use the contactid as subscriber relationship, contacts are not getting injected into the journey. I have to change the subscriber relationship to email address in order for journey to work.