That's a great question! It's definitely a good idea to clean up your contacts and lower your bounce rate. Having your contact whitelist you in their email account or security program are both great steps to take. I took a closer look at your bounces and can see they mostly bounces as undeliverable, non-existent, suspended. For these we recommend removing them or even double-checking for any addresses listed incorrectly so they can be updated. However if you know the address is correct (for example, you've successfully communicated with it outside of Constant Contact recently), please call into our Deliverability Department for further assistance. These support agents can help look further into these contacts. We also have an article in our Help Center that shares more tips on what to do with these bounced contacts and how to prevent future bounces from happening.