What is email bounce rate?



In email marketing, bounce rate refers to the percentage of email addresses in your subscriber list that didn’t receive your message because it was returned by a recipient mail server. There are two categories of email bounces including hard bounce and soft bounce.

What does a hard bounce mean?

This means an email has bounced back to the sender, undelivered, and without having been accepted by the receiving email server. The usually given reasons for a hard bounce are:

What does a soft bounce mean?

Soft bounce is used to describe an email that has bounced back to the sender, undelivered, due to a temporary error. The usual reasons for this situation are:

At mailfloss, we usually recommend removing email addresses that are full because we believe these are of low quality, potentially abandoned, and will hurt deliverability over time.

Due to some verification tests and aggressiveness options, sometimes an email gets delivered to an address we flagged, this is what we call a false positive. This usually happens with Accept All addresses and increases if Aggressive mode is enabled. Learn more about false in this article.

Sometimes you may find that you got a bounce from an email address that seemed to be “good” and passed verifications tests. This is what we call a false negative, and you can learn more about false negatives here. This usually happens with Normal mode as we don't run our full gamut of tests. 

At the end of the day, our mission at mailfloss is to help you maintain a clean and healthy list, without sacrificing all those hard-earned leads and subscribers. That's why we usually recommend Normal mode for most users to maintain a healthy bounce rate, as flossing too aggressively will potentially remove too many false positives and remove perfectly valid email addresses.