Cleaning your Klaviyo list is not hard. You can do it step-by-step. It's like cleaning your room, one area at a time. The main goal is to find people who are not engaging. Then you decide what to do with them.
First, you need to find out who is inactive. Klaviyo has great europe cell phone number list tools for this. You can create special groups called "segments." These segments help you organize your contacts. You can tell Klaviyo to show you people who haven't opened an email in a long time.

Second, you try to get those inactive people interested again. This is called a "re-engagement campaign." You send them special emails. If they don't respond, then it might be time to say goodbye.
Using Klaviyo Segments to Find Inactive People
Klaviyo lets you create very smart segments. You can set rules for these segments. For example, you can make a segment for "Subscribers who have not opened an email in 90 days." Or "People who haven't clicked a link in 180 days." You can even add a rule for "Has not placed an order in 365 days."
Start by defining "inactive." For some businesses, 90 days of no activity is inactive. For others, it might be 6 months or even a year. Think about how often you send emails. If you send often, a shorter timeframe for inactivity makes sense. If you send emails only sometimes, a longer timeframe is better.