Email Deliverability

Difference Between Hard Bounce and Soft Bounce

Post by
Lara Bingel
Difference Between Hard Bounce and Soft Bounce

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Decoding Bounced Email Notifications

Opening your inbox to see notifications of bounced emails can be a bruise to your ego. But before you panic, keep in mind that email bounces can be an important learning opportunity.  

Use it to gain more insights on how to further improve deliverability and prevent you from losing re-engageable contacts.

In this article, we’ll unpack the differences between soft bounces and hard bounces, their underlying causes, and most importantly—how to handle them without sabotaging your sender reputation. Keep reading to gain insider intel to understand and diagnose why deliverability failed.

Unpacking Differences: Soft Bounce vs. Hard Bounce

Soft bounce vs hard bounce

Not all bounces are created equal. There are two main categories of email bounces: soft bounces and hard bounces. Understanding the differences can help you properly manage your email list and keep your sender reputation intact.  

What is a Soft Bounce?

A soft bounce occurs when an email is temporarily rejected by the receiving server.  

Some common triggers include:

  • Full inbox: The recipient's inbox is full so the email could not be received.
  • Temporary connectivity issues: A possible server outage or issue prevented delivery from either recipient’s or sender’s end,
  • Authentication issues: Your email does not meet the (DMARC) policy.
  • Type of content: The recipient has spam filters that are blocking your email due to content.
  • Message size: Too many attachments or too large of an attachment was included in the email.
  • Temporarily inactive: The mailbox you’re trying to reach is temporarily inactive.
  • Suspended account: The recipient’s email has been suspended.
  • Email blocked by ISP: The recipient’s domain had blocked messages from your sending IP.
  • Spam complaints: The contact had manually reported and marked your messages as spam.

What is a Hard Bounce?

A hard bounce occurs when an email is permanently rejected by the receiving server.

Some common triggers include:

  • Invalid email address: Due to either a mistype or fake email address.
  • Inactive email address: Email has been abandoned, deactivated or deleted.
  • Server related issues: The email server on the recipient’s end has blocked your delivery.

Managing Bounces: How to Troubleshoot

The key difference lies in recoverability. Soft bounces represent temporary issues you should monitor while hard bounces require permanent removal.

For soft bounces, most email providers will continue to try to deliver the email over a certain period of days. If a contact continues to have repeated soft bounces that are spanning over longer periods, flag them to monitor. But keep attempting re-engagement in case problems are temporary.

Note: It’s important to address the reasons behind why the soft bounce occurred first and to resolve accordingly before trying again.

For hard bounces, these indicate more serious issues with about 95% of the time being due to invalid addresses, so it’s best to remove them completely from your list. Continuing to send to recipients who have invalid emails leads to damaging deliverability and sender reputation.  

Note: When diagnosing bounces, first ensure if failures are consistent over time or are short-term ISP blocks. Also, it doesn’t hurt to check if alternative addresses exist before entirely removing contacts—this helps in not losing any potential leads.

Depending on your ESP, it may or may not automatically try to resend soft bounced emails within a certain amount of time after initial sending. Certain platforms also may or may not require you to manually remove any email address which hard bounced.

For Mailivery users, once the system has detected a hard bounce from your account, it will automatically stop sending to these indicated emails. This is to avoid ‘bad’ emails affecting campaign performance and to maintain good sender reputation.

Bounce Management is Crucial for Email Success

Learning how to handle email bounces properly is crucial for list management and sender reputation. Understanding the core differences between soft and hard bounces will determine what kind of troubleshooting strategies to enforce for better bounce management.

It's easy to feel defeated by those error notifications.

However, with the right mindset, you can transform bounces into teachers rather than barriers. By doing so, you gain actionable troubleshooting tips to nurture deliverability and maintain a good sender reputation.

With the right response to each bounce type, you’re on your way to achieving better campaign performance with clean lists and optimal deliverability—all which supports in maintaining a good sender reputation.

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