The Difference Between a Hard and a Soft Bounce

The term “bounce” as it pertains to email analysis is never a good one. Put simply, a bounced email means that your email was not delivered to the intended recipient. There are a number of reasons that a bounce may occur, but they are divided into two broad categories: a hard bounce and a soft bounce.

So what’s the difference between a hard bounce and a soft bounce, and why does it matter for tracking email metrics?

Hard Bounce vs. Soft Bounce

In the simplest possible terms, a soft bounce is when an email is delivered to a valid email address but gets rejected for temporary reasons. One of the most common reasons that a soft bounce occurs is because an inbox is full, meaning the message cannot be delivered. Another reason for a soft bounce is a temporary hardware failure: for example, if an email server goes down because of a power outage or natural disaster. Email size is another common reason for a soft bounce. Many companies and ISPs have limits on the size of an email and will reject any that exceed this limit.

On the other hand, a hard bounce is more of a permanent rejection. A hard bounce happens because the recipient’s address is not valid. Hard bounces may occur for several reasons: the address syntax was incorrect, the address does not exist, or the mail server has moved to a new location.

The other big difference between a hard bounce and a soft bounce is what you should do about them.

Handling a Hard Bounce and a Soft Bounce

When a hard bounce occurs, it’s a good sign that you should take that particular contact off your list. They have either changed email addresses or their mail server has changed. If it’s a business address, it’s possible that the employee has moved on and the company has deactivated their address.

On the other hand, your reaction to a soft bounce isn’t so cut and dry. There’s a chance that you might be able to immediately identify the reason that your email didn’t go through and correct it. For example, if you are attaching a big file to your email correspondence, try to either remove the file or cut down its size and resend your message. You could also wait for a period of time. If the person has a full inbox, they may be on vacation or extended leave, meaning it will not be cleared until they get back.

Whatever the reason is that your email has bounced, it’s important that you rectify the situation as soon as possible. A high bounce rate will lower your sender score, which gives you a better chance of ending up on ISP blacklists, or in the spam folders of your recipients’ inbox. The most important step to avoiding bounces is to understand them and maintain an awareness of when and why they happen. If you track your email metrics carefully and act on the data that you find, it will be easy to reduce your bounce rate so that more of your messages get through to their intended recipients.