What Is a Soft Bounce?
Definition
When an email is temporarily undeliverable, that means it was soft bounced. This is different from a hard bounce, which totally blocks email communication. Soft bounces usually happen when the recipient has a full inbox. It could also be due to an issue with the server being used or the email being bigger than the recipient’s mailbox size limit.
In most cases, soft bounced emails are delivered to the intended recipient once the issue’s fixed. This issue appears on an email report as a “soft bounce,” and suggestions to address the issue are also provided.
Example
For example, a software company sends a product update email with a large PDF attachment to their mailing list. Many recipients experienced soft bounces because the size of the attachment was too big for their email server to receive. Because of this, the company compresses its attachment size and takes note of the ideal sizing for future campaigns.
Common Causes of Soft Bounces
Around 0.41% of all emails worldwide bounced in 2024. Here are the most common reasons why a soft bounce might happen:
- Full Inbox: The recipient’s inbox has reached its storage capacity.
- Server Downtime: The email server is temporarily unavailable or is experiencing connectivity issues.
- Large Attachments: The email exceeds the recipient’s mailbox size limits.
- Non-compliance: The email doesn’t meet the recipient’s antivirus or anti-spam requirements.
- DMARC Failure: The email did not pass DMARC’s authentication checks.
How to Address Soft Bounces
Soft bounces happen when an email can’t be delivered temporarily, but there are steps you can take to address them effectively and minimize their impact on your campaigns. Start by monitoring bounce reports provided by your email service provider (ESP). These reports give detailed information about which emails bounced and why, helping you identify patterns or recurring issues.
One of the simplest fixes is to retry delivery after a short period. Giving the server some time before resending can solve the problem without additional effort. Since soft bounces are also caused by large file attachments, optimize your email’s file size by compressing images or hosting larger files on external platforms and linking to them instead. Lastly, maintaining a clean email list through regular validation is key to reducing bounce rates. Removing invalid or inactive addresses helps keep your campaigns targeted and ensures you’re sending to recipients who are more likely to engage with your content.
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