If you see a high bounce rate in your campaign report, there are several reasons why this may be happening.

Your List Import Had Errors

Sometimes, .CSV files need to be checked for formatting errors before you import and can cram extra information into important fields in your list, like the email address field. To check if there were formatting errors on your list import, navigate to the Lists page in your account and click the name of the list to view its subscribers and determine if you see anything out of place or any extra information crammed into the email address field.

Your List is Old

If you see high bounce rates and your list is relatively new or not regularly used, it may include stale or inactive addresses.

Your List Contains Bad Data

If your list is brand new, and already showing high bounce rates, it may be a problem with where the list came from or how it was compiled. Take some time to determine if your list is okay to use.