Soft Bounce vs Hard Bounce: What’s the Difference?


A bounce occurs when a recipient’s mail server rejects an email. Much like SPF, DKIM and DMARC, this may seem like a technical email issue, but ultimately a bounced email means your intended recipient will never see your message and that could mean a significant loss of revenue. 

A bouncing email could stem from several different reasons. It could range from the recipient’s mailbox being full, to the domain name not existing. What differentiates a soft bounce from a hard bounce? One is permanent, and the other is not. We highly suggest paying attention to bounce logs, as bounces impact deliverability reputation.

The lighter of the two, a soft bounce, results when an email reaches the recipient’s mail server but bounces back before it makes it to the recipient. Soft bounces ensue from a recipient’s mailbox being full, the email server being offline or rate-limiting the number of messages it receives, or the message itself being too large. Retry sending to a soft bounce for up to 72 hours for one campaign, and then suppress the email address for that campaign. If a contact soft bounces for multiple campaigns, suppress the email address entirely.

Soft Bounce Causes:

  • Full mailbox
  • Offline or rate-limiting mail server
  • Too large of an email


  • Retry several times, then suppress for that campaign. Retry in the next campaign. If it still doesn’t deliver, stop sending to the contact.

Hard-bounced emails have returned to the sender because of a permanent failure, which means retrying won’t change the outcome. These negatively affect email deliverability. Some of the more common hard bounces ensue from the recipient’s address being invalid, the domain name not existing, or the receiving server blocking delivery from your domain or IP address. Hard bounces result from a poor sending reputation, and they also cause a poor reputation if unchecked.

Hard Bounce Causes:

  • The email address doesn’t exist
  • The domain name doesn’t exist
  • The recipient’s email server has blocked the emails


  • Immediately stop sending to the contact
  • Analyze the most common bounces to determine the source of the bad addresses

When focusing on needed email deliverability efforts, understand the difference between a soft bounce and a hard bounce. A significant percentage of hard bounces indicates an unhealthy list, so pay special attention to those and take action to analyze your list and clean it where needed.

For more information on deliverability problems, contact us.

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Soft Bounce vs Hard Bounce: What’s the Difference?

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