What can I do to reduce the number of bounces?
There are a few steps you can take to reduce the number of bounces in your email marketing campaigns. Bounce rates of as little as 1% can significantly impact your email delivery.
The reason those list types are not allowed is because lists of that nature yield high bounce rates and generate spam complaints. So make sure you are using a closed-loop (also known as double) opt-in list of contacts that have asked to receive email from you directly.