Please note that this is the help section for the former Newsletter2Go software.

Are unsubscribed addresses and bounces overwritten when importing a new list?

No. You can simply import the entire list again. 

When importing a list, contact data is automatically synchronized and updated, so unsubscribes and bounces are identified and not overwritten, whilst new contacts are added.

The system automatically filters out duplicates when you import a new list, so you do not need to cleanse your lists manually beforehand.