What is the difference between soft bounces and hard bounces?

When you send a mailing, there is a chance that, for some recipients, your message might not arrive. In email, we call this 'bounces' and we distinguish between soft bounces and hard bounces.


Soft bounces

A soft bounce usually indicates a temporary problem in delivering your message. For example, because your recipient’s mailbox is full, because the mail server is temporarily unavailable, or because the message is too big.

In this case, a subscriber first ends up in the Soft bounce (1x) group, then in the Soft bounce (2x) group and finally in the Soft bounce (def) group. If a subsequent mailing was delivered successfully, the subscriber is automatically removed from this group.


Hard bounces

A hard bounce means there is a permanent reason as to why a message cannot be delivered. Possible reasons include: the recipient’s email address doesn’t exist (anymore), the domain name doesn’t exist or the recipient’s mail server blocks all forms of traffic (from your server) (spam block).

If one of your emails shows a hard bounce, it will first end up in the Hard bounce (1x) group, then in the Hard bounce (2x) group and finally in the Hard bounce (def) group. In case of a hard bounce during the very first mailing within a campaign, the subscriber will immediately be sent to the Hard bounce (def) group, without any in-between stops in (1x) or (2x).


Lowering your bounce rates

When it comes to reducing bounce rates, focusing on hard bounces is key. However, that doesn’t mean you don’t have to pay any attention to soft bounces. For example, an out-of-office reply may include information to prevent future hard bounces. Like a notification that someone’s email address will be terminated soon because they no longer work for the company.

Make sure people do not enter a wrong address. Typos can happen easily, and people commonly enter the wrong email address by mistake. You can prevent this by asking people to enter their email address twice. Or, better yet: by using a double opt-in, with which you let someone confirm a subscription to a newsletter with a link in an email, for example.