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

By Cathy Grendus

Published on 9 Nov, 2021

You’ve heard of an email bounce, but you might be wondering: what does it mean when an email bounces?

What Is a Bounced Email?

An email bounce occurs when a recipient’s mail server rejects an email. An email bouncing on a server can happen for a multitude of reasons. 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. Sometimes the content of the email is the issue – read more in our blog post 30 Spam Filter Words and Phrases to Avoid to see more. The reason for a bounced email can vary; it isn’t always one reason and can be a combination of many. 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. Here are the two types of bounce email meanings: a hard bounce is a permanent issue that cannot be resolved without action, while a soft bounce may only need time to resolve itself.

We highly suggest paying attention to bounce logs, as bounces impact deliverability reputation. Many popular email platforms like Mailchimp and Mimecast track the types of bounces in their reports. A hard bounce Mailchimp detects will be flagged just as a soft bounce Mailchimp detects will be counted, to help you determine which problems you may need to investigate when emails are bouncing servers.

Soft Bounces

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

Actions to Take to Prevent Soft Bounces:

  • 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 Bounces

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 bounces may mean that you’ve been added to an email blocklist or something is wrong with the delivery. A blocklist could be affecting your sending reputation to the point that you won’t be able to reach your audiences. To read more about email blocklists, check out our article Blacklists or Blocklists Every B2B Enterprise Email Marketer Should Avoid.

Hard Bounce Causes:

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

Actions to Take to Prevent Hard Bounces:

  • 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. Plenty of email service providers offer tracking for these types of bounces: Mailchimp hard bounces and Mimecast hard bounces are recorded. Reach out to your personal provider if you cannot find a bounce log.


What does it mean to bounce a server when you’re email marketing? Nothing good, so keep track of your hard and soft bounces throughout every campaign. Hard and soft bounces matter for your email deliverability and could cost you money with every customer blocked.

Shift Paradigm is an experienced full-service team that makes a perfect partner for every business. We’re happy to answer any further questions about bounce rates and work with you to solve them. For more information on deliverability problems, contact us.

Written By Cathy Grendus

Cathy Grendus, VP, Marketing Strategy & Planning at SH/FT leads a passionate team of marketing, strategy, and creative professionals. Her extensive 1:1 direct mail, digital and email marketing expertise - working with clients within various industries (including not-for profit, financial services, CPG, energy, grocery, retail, healthcare, and consumer electronics/technologies), and experiences as a Canadian Marketing Association awards judge, has led to her being a well-respected leader in the industry. Through her true understanding of the potential contention of left brain vs. right brain in the world of marketing – and has resolved to merge the two together at every opportunity in order to provide the most optimal results through insights-driven campaigns.
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