Understanding Soft Bounces vs Hard Bounces in Email Deliverability

Sending emails is a great way to reach your audience, but not all emails sent will make it to the recipient’s inbox. Sometimes emails bounce back and this can happen for several reasons. As an email marketer, it’s important to understand the difference between soft and hard bounces so you can properly handle them. In this comprehensive guide, we’ll break down what exactly soft and hard bounces are, what causes them, and how to deal with them to maximize your email deliverability.

What is a Bounce in Email Deliverability?

First, let’s start with understanding what a bounce actually is. A bounce occurs when the email you sent cannot be delivered to the recipient’s email inbox. Instead of the email reaching the inbox, it bounces back to you, the sender.

There are two main categories of bounces

• Soft bounce
• Hard bounce

The main difference lies in the nature of the bounce. Soft bounces are temporary failures while hard bounces are permanent failures.

Soft Bounce

A soft bounce is a temporary failure in email delivery Some common triggers for soft bounces include

• Recipient’s inbox is full
• Mailbox exceeds quota
• Recipient server is down or offline temporarily
• Message too large for recipient server
• Domain name does not exist temporarily
• Spam filter blocking

With a soft bounce, the sender server will continue trying to re-send the email for a period of time, usually a few days. Soft bounced emails may eventually reach the recipient inbox once the temporary issue is resolved.

As an email marketer, soft bounces signal issues you should monitor but not completely remove from your list immediately. You’ll want to note any addresses that soft bounce repeatedly and eventually remove them if the soft bounces don’t resolve.

Hard Bounce

A hard bounce signals a permanent failure in email delivery. Some triggers of hard bounces:

• Recipient email address does not exist
• Email domain does not exist
• Recipient server blocks emails permanently

With a hard bounce, the email is permanently undeliverable to the recipient address. Senders will receive a failure notification right away and the recipient address should be removed from the email list.

Hard bounces signal dead or invalid email addresses that should not receive any more emails. Continuing to send to hard bounced addresses will likely hurt your sender reputation.

Causes of Soft Bounces vs Hard Bounces

Now that we understand the difference between soft and hard bounces, let’s look at some of the most common causes for each bounce type.

What Triggers a Soft Bounce?

• Full inbox or quota exceeded: The recipient email box is over the allowed storage limit so new messages are rejected. This is one of the most common soft bounce causes.

• Inactive or invalid mailbox: The recipient mailbox is not able to receive new messages due to a technical issue on their end.

• Server unavailable: The recipient’s email server is down or unreachable so the message cannot be delivered.

• Message too large: Individual servers will have size limits on emails. If your message exceeds the limit, the recipient server will soft bounce it.

• Temporary domain issue: Your recipient’s domain name has an issue that prevents emails from being received. This may be an expired domain registration.

• Spam filters: Recipient spam filters may temporarily block your email from entering the inbox until deemed safe.

• Security policies: Your email content triggered a security scan that temporarily blocked delivery. Malware threats may also be blocked until proven safe.

• Reputation-based blocks: If your sender reputation is poor, recipients can temporarily reject your emails until you improve your standing.

What Triggers a Hard Bounce?

• Non-existent user: The recipient email address itself does not exist so your message cannot possibly be delivered. This is the most common hard bounce.

• Invalid domain name: You sent to a domain name that does not exist or has expired registration. Emails to the entire domain will hard bounce.

• Shut-out sender: The recipient server has blacklisted your specific email address or domain from sending any emails.

• Blocked at IP level: Your sending IP address has been permanently blocked and blacklisted by the recipient server.

• Full block on domain: The email domain you are sending from is permanently unable to send emails to the recipient domain.

• Email account closed: The recipient email account has been deactivated or deleted so your emails will not deliver.

• Email address format invalid: You have an incorrect email format that triggers an immediate hard bounce.

• Hard security block: Your email content, links, or attachments triggered a permanent block by security filters.

Soft Bounce vs Hard Bounce Rate

In addition to causes, email marketers should be aware of healthy bounce rates to aim for deliverability success.

Industry experts recommend keeping your hard bounce rate under 2%. A high hard bounce rate signals major issues with your list hygiene and targeting.

Soft bounce rates can be slightly higher than hard bounces, but you still want to aim for less than 5%. Consistently high soft bounce rates indicate potential trouble spots.

Benchmarks aside, focus on keeping both bounce rates as low as possible. Monitor your email campaigns frequently and remove or reactivate problem addresses as needed. List hygiene is just as important as well-designed email content.

How to Handle Soft Bounces vs Hard Bounces

Now that you know how soft bounces and hard bounces work, let’s look at how you should actually handle them:

Handling Soft Bounces

With soft bounces, you don’t want to take immediate action and remove addresses. Since soft bounces are temporary, these emails may still deliver once the problem is fixed.

Here are tips on working with soft bounces:

• Note any repeat offenders soft bouncing each campaign.

• If an address soft bounces 3-4 consecutive campaigns, remove from active list. You can export and save in a reactivation list.

• Monitor your soft bounce rate each campaign. Aim to keep it under 5% overall.

• A sudden spike in soft bounces likely signals a delivery issue on your end to quickly address.

• Re-engage with soft bounced subscribers to prompt list updates and inbox checks for your emails. Directly ask them to add you to contacts, check spam folders, etc.

• Use an email validation service to confirm soft bounced addresses are still accurate and active for future reactivation.

With effort, you can turn some soft bounces back into active, engaged subscribers.

Handling Hard Bounces

Hard bounces require more decisive action. Since the failures are permanent, you’ll need to remove these addresses to keep your list clean and sender reputation secure.

Here are tips for managing hard bounces:

• Remove hard bounced addresses from your active email list ASAP to avoid continued delivery failures.

• Export and save hard bounces separately if you need to retain records. For example, you may need to note clients or leads that bounced.

• Review your signup process if you’re seeing an abnormal spike in hard bounces. This could indicate problems collecting addresses.

• Check your email content and subject lines against common spam trigger words that could be causing blocks leading to hard bounces.

• If a domain or sending IP is getting blocked frequently, contact the provider to troubleshoot and see if the ban can be lifted.

Hard bounces need to be pruned completely from active campaigns. Be vigilant about checking bounces after each email send and take action promptly.

Email Deliverability Tools to Handle Bounces

Managing bounces works best when you have the right tools to stay on top of your email deliverability. Here are some must-have tools:

• Email validation service: Validate the accuracy and quality of your list both before sending and after bouncing. Double opt-in confirmations can help too.

• Bounce tracking and notifications: Your email service should track bounces and immediately alert you when they happen. Watch for bounce spikes that indicate issues.

• Bounce management automation: Set up rules to automatically remove hard bounces from your active lists to keep them clean.

• Bounce analysis: Review bounce reasons and trends frequently. Identify any problem domains, addresses, or campaigns causing elevated bounce rates.

• Sender reputation monitoring: Use tools to monitor your domain and IP sender reputation to catch issues before major impacts happen.

• Spam filter checks: Submit emails to preview tools to safely test spam filter blocking before sending.

Using the right mix of email deliverability tools takes the hassle out of managing bounces. You can act faster on insights to optimize your campaigns.

Soft Bounce vs Hard Bounce: Key Takeaways

Understanding the difference between soft vs hard bounces is key for email marketers. To recap:

• Soft bounces are temporary delivery failures while hard bounces are permanent failures.

• Soft bounces may still reach the inbox eventually while hard bounces will never deliver.

• High soft bounce rates indicate potential list or deliverability issues to address.

• High hard bounce rates signal serious list hygiene problems requiring immediate action.

• Monitor bounce rates closely each campaign and use