A high email bounce rate is when more than 2% of your emails fail to reach recipients. You should avoid high bounce rates to maintain a good sender reputation. You can experience a high bounce rate due to invalid email addresses or outdated lists. You must clean your email list regularly to prevent this. You should also check if your emails are getting blocked by spam filters. A high bounce rate can affect your deliverability and result in your emails being marked as spam. You should focus on improving list quality and verifying email addresses to reduce bounce rates.