How to fix and prevent bounced emails

In this article, you will learn what hard/soft bounces are, common delivery errors, why they happen, and how to fix them.

Bounces are email delivery errors that occur when emails fail to reach their intended recipients and are returned to your inbox.

Before we start, here are brief steps on how to identify bounces: 

a) Send a test email from your primary email address (which sends campaigns) with your usual email content to your other email address.

If you receive a bounce-back message in your inbox, open the delivery error report and review the information.

b) Check your inbox for undeliverable emails. These emails typically have subject lines such as “Mail Delivery Subsystem” or “Your message couldn’t be delivered.”

Examine the bounce reports for any recurring patterns or errors.

Bounce reports from email providers help determine the specific reason why the email could not be delivered.

Moving forward, we will outline the most common bounce examples to help you fix and avoid them in the first place.

Bounce types

There are two main categories of delivery errors: hard bounces and soft bounces.

Based on what type of bounces you get more often, you can take necessary actions to fix them and decide whether to continue sending your campaign bounced emails.

Hard bounces

A hard bounce is a permanent delivery error. Any future attempts to send emails to that email address will most likely fail again. 

1) Address not found

This delivery happens when the recipient’s email address is invalid or the email account was deactivated. 

2) Message blocked

This bounce occurs when the recipient’s email server rejects incoming emails.

• If a recipient has a spam filter which checks email components (subject lines, email content, any emails that don’t meet the spam filter criteria will be blocked.
• If the recipient’s email server has a policy to block emails from certain sender IP addresses or domains, emails will be automatically rejected.

Soft bounces

Soft bounce is a temporary delivery error and the email might still be delivered successfully after you fix the issue or retry. 

1) Message not delivered: When the recipient’s server isn’t able to accept the email.

This delivery error happens due to a temporary server error or connection timeout while sending the email. 

2) Recipient inbox full

It happens when there is no more space in the recipient’s email client for new incoming emails or when it receives too many emails at the same time.

3) Delivery incomplete: When the recipient’s server is temporarily down or unavailable.

Like the “Message not delivered” error, emails cannot be delivered if the recipient’s server doesn’t respond.

Usually, your email provider will try to resend the email automatically a few times.

4) Daily sending limit exceeded

This delivery error happens when you reach the daily/hourly sending limit set by your email provider.

5) Email size is too large

Your email exceeds the maximum size limit allowed by the recipient’s email server. 

How to prevent bounced emails

Lots of bounced emails can really damage your reputation as a sender. Make sure to handle it right to avoid harming your deliverability and campaign results.

# Monitor your bounce rate 

Snov.io automatically detects bounced emails in active campaigns and stops sending the sequence to that recipient.

Read how to troubleshoot high bounce rate issue → 

# Take care of your sender reputation 

The root cause of many bounces is a low sender reputation, which causes receiving email servers to reject emails.

A low sender reputation is caused by factors such as poor engagement, high complaint rates (when recipients report emails as spam), and a lack of domain configuration.

Read Email best practices → to improve your sender reputation and email engagement over time. 

# Authenticate outgoing emails

Email service providers also check authentication to evaluate senders’ reputation. Emails that fail authentication checks may also bounce.

To authenticate your emails, set up SPF, DKIM, and DMARC records in your domain’s settings.

–> Set up SPF  

–> Set up DKIM

–> Set up DMARC

# Test deliverability before sending campaigns

Perform email placement tests with Snov.io Deliverability check to identify any potential issues with email delivery and take necessary steps.

As an extra step, monitor and evaluate email delivery using tools like Google Postmaster Tools and Microsoft SNDS.

Additionally, check your IP address and domain against popular blacklists.

Read how to deal with blacklisting →

If tests show poor deliverability:

• Pause your active campaign. Start a warm-up process for the email account that sends it.
• Continue warming up after restarting the campaign.