How Can I Make Sure That Certain Users No Longer Receive My Newsletter?

There are three options:

1. If a user unsubscribes via the unsubscribe link in your email, they will no longer receive any newsletters. In this case, no further action is necessary. 

2. You can create a list (e.g., Excel or CSV) containing all email addresses of customers who no longer wish to receive your newsletter. You can then import this list into your Newsletter2Go account with all users set to "Blacklist". 

3. You can also unsubscribe users manually. Search for their email address under "Contacts" --> "Active Contacts" --> "Advanced Search". Click on the gear icon next to their email address and select "unsubscribe" from the drop-down menu. "Global" will mark them as unsubscribed across all contact lists within your account, whereas "this contact list" will mark them as unsubscribed in the selected contact list only.