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

April 16, 2024 Email Templates, Email Tool
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soft bounce vs hard bounce email

If you’re a marketer, you must have had an email bounce back to you. But, not all bounces are the same. That’s why you must know the difference between soft bounce vs hard bounce email for good sender reputation and delivery.

Soft bounce is a temporary email delivery issue, often due to a full mailbox or server downtime. In contrast, hard bounce is a permanent delivery failure, typically caused by invalid recipient addresses or blocked domains. 

However, that’s not the end of it. In the upcoming sections, we’ll explore what causes them, how they affect your email delivery, and what you should do if you get these bounce alerts. It’ll help you manage bounces better and improve your sender score.

What is a Bounced Email?

A bounced email is one that didn’t reach the person you sent it to. The email server might block it, either just for now or forever. If this happens, you usually get a message back saying your email bounced.

Moreover, the email bounce rate varies by industry as you can see from the chart.

What is a Bounced Email

What’s Included in a Bounce Email?

The bounce message can tell you why your email didn’t get through. It usually includes —

  • When the email bounced.
  • Which email server blocked it.
  • A technical code (RFC code) that explains why it bounced. But, not all email services use these codes the same way.

Why Do Emails Bounce? 

Emails can bounce back for several reasons. Common causes include —

  • The recipient’s email address is incorrect.
  • The recipient’s server is down, or their inbox is full.
  • Your email is marked as spam or fails DMARC policy checks.

How to Calculate Bounce Rate

To find out your email bounce rate, use this simple formula —

(Bounced emails ÷ Total emails sent) x 100

This calculation will give you a percentage that represents the rate at which your emails are not reaching their intended recipients. To get a deeper understanding of your email bounce rate’s impact on sales performance, you must know how to analyze sales data effectively.

Hard Bounce vs Soft Bounce: A Quick Comparison Table

Take a look at our table to grasp the differences between these two critical parts of email marketing.     


Hard Bounce

Soft Bounce

What It Is

An email that can’t be delivered and won’t ever get through.An email that didn’t deliver now, but might later.
Main ReasonsWrong email address, or the email domain doesn’t exist.

Recipient’s inbox is full, or their email server is having issues.

Effect on You

Hurts your email reputation. Remove these emails from your list.Not as harmful, but keep an eye on these. If they keep happening, remove them too.
Typical Error CodesUsually shows a 5XX error.

Usually shows a 4XX error.

What to Do

Take these emails off your list.Try sending it again later. If problems persist, remove them.
ExamplesEmail address is fake or doesn’t exist.

Mailbox is too full or the server is temporarily down.

Handling in ESPs

Most email systems will automatically stop sending to these.They’ll try to send these emails again. If they keep failing, they’ll stop.
Preventing IssuesRegularly clean your email list and check for correct emails.

Make sure your emails aren’t too big and follow good email practices.

Long-Term Impact

This can lead to more of your emails being marked as spam.

It can cause some delivery delays, but usually not a big problem.

What is a Soft Bounce Email?

A soft bounce email is one that temporarily can’t be delivered. This might happen if the recipient’s inbox is full or the email is too big. Email services usually try to send these emails again over the next few days. 

If you keep seeing soft bounces from the same email addresses, it’s a good idea to remove them from your list. In short, a soft bounce means the email couldn’t be delivered temporarily.

Look, dealing with soft bounces efficiently requires a smart approach. In that case, email marketing automation can simplify this process for better results.

Common Causes of Soft Bounces

Soft bounces can happen for various reasons. Some are minor issues, but others might hint at future hard bounces. The usual causes include —

Common Causes of Soft Bounces

1. DNS Failure or Other Errors

This happens when there’s a problem with the Domain Name System (DNS) on the recipient’s side. It could mean their email server was down or set up wrong. 

If this is the case, the email will probably be tried again over a few days. If it keeps failing, it might become a hard bounce.

Sometimes, this error shows up if the domain you’re sending to doesn’t exist. Then, the email won’t be tried again, and you’ll need to find another way to contact the person.

For example, the connection might time out. The server will usually try to send the email again later before giving up.

What Can You Do?

If you encounter a soft bounce, wait a day or two and try sending the email again. If the issue was temporary, it should be fixed quickly. You can also reach out to the recipient through a different method to confirm their email address.

Moreover, when DNS failures lead to soft bounces, having alternative contact methods is key. Find out how to easily find email addresses by phone number.

2. Full Mailbox

When an email can’t be delivered because a mailbox is full, it’s usually a hard bounce. But sometimes, it starts as a soft bounce. Imagine you’re sending emails to a customer. They used to get and open these emails, but now they’re not getting through. 

The Internet Service Provider (ISP) keeps trying to deliver these emails for a couple of days. During this time, the email is considered a soft bounce. If after two or three days the email still can’t be delivered, it becomes a hard bounce.

If a full mailbox issue continues for a while, the ISP might begin to treat these as hard bounces more often. It typically happens if a customer hasn’t checked their email in a long time and their mailbox is full.

What Can You Do?

Contact your customer to tell them their mailbox is full. Ask if they have a new email address. If the email keeps bouncing, it’s best to remove it from your list.

3. Handling Autoresponder Emails

When you send out emails to a large group, especially during the holiday seasons, you’re likely to receive many automatic replies. Most of these autoresponders will inform you that the recipient is temporarily unavailable, like being out of the office, and will look at your email later. 

In such situations, your email has successfully reached them, so there’s no immediate action required on your part. However, if you don’t get a response after a few days, it’s wise to follow up.

Paying attention to the content of these autoresponder emails is crucial. They can sometimes inform you that the person you’re trying to reach has left the organization. 

Often, companies keep these email accounts active and include information about whom to contact instead. If you come across such information, it’s important to update your mailing list accordingly.

What Can You Do?

Autoresponder emails are different from email delivery issues like soft bounces or hard bounces. There’s no need to delete these email addresses from your list. The recipients will eventually see your email once they resume checking their emails regularly.

4. Other Errors

Sometimes, when an email doesn’t get delivered, the Internet Service Provider (ISP) might send back a vague error message. 

These are known as “Other” bounces. We treat these as a soft bounce because we can’t pinpoint the exact problem. Often, these are due to technical issues, like a connection timing out.

What Can You Do?

Check with the recipient to see if they have a new email address. If you’re sure the email address is correct but still facing issues, it’s a good idea to contact our Support Team for help.

If the email keeps failing to deliver, consider removing the address from your list.

Additional Tip: If someone says they’re not getting your emails but they’re not on your bounce list, ask them to check their spam folder. 

If your email isn’t there, they can add your email address to their safe sender list in their email settings or security software. It can help prevent future email bounces.

What is Hard Bounce Email?

A hard bounce email is one that permanently can’t be delivered. This might be because the email address is fake, the domain doesn’t exist, or the recipient’s server rejects emails. Essentially, a hard bounce means the email will never get through. 

You should remove these email addresses from your list as they represent permanent delivery failures.

Common Causes of Hard Bounces

Hard bounces can occur for several permanent reasons —

Common Causes of Hard Bounces

1. The Recipient Doesn’t Exist

This means the email address you’re trying to reach isn’t real. It could be due to a typo or a domain that doesn’t exist. Sometimes, it’s because the person no longer works at a company and their email has been deactivated. 

This situation often results in a 550 5.5.1 server error. If you see this error, it’s a clue that the email address might be wrong.

What Can You Do?

Carefully check the email addresses for mistakes. Plus, reach out through another method to see if the recipient has a new email address. If you correct any errors, try sending the email again.

2. Spam Filters Rejecting Email

Sometimes, your email or its subject line might be marked as spam by an Internet Service Provider (ISP). ISPs often decide what’s spam based on how their customers interact with emails. 

For instance, if someone never opens your emails, your next email might go straight to their spam folder.

If someone has labeled your email as spam before, there’s a high chance your future emails will also be seen as spam, even if they signed up for your emails.

What Can You Do?

Consider sending emails less frequently, changing your content, or removing them from your email list if a customer rarely opens them.

Always check your emails for spam before sending them. You’re in charge of your email content, so use a spam checker tool. Make sure you know the automated tools your email service provider uses to help with this, like Mailchimp soft bounce handling.

3. Managing Full Mailbox Issues

Every email inbox has a limit on how much data it can hold. Once this limit is hit, any new emails sent to it will probably bounce back. Sometimes, email providers might try to send the email again after a few days. If this happens, it’s known as a soft bounce.

However, it’s not always wise to rely on this. If you’re notified that an email couldn’t be delivered because the mailbox is full, consider contacting the recipient in a different way. 

They might not know their inbox is full. Often, a full mailbox could mean the account isn’t being used anymore. In that case, it’s better to find another way to get in touch.

What Can You Do?

Contact the recipient to inform them that their mailbox is full. Ask if they have a new email address. If emails to the address continue to bounce, it’s best to remove it from your email list.

4. Email Blockages by Servers

Sometimes, modern email servers block emails they think are unwanted. This can cause problems with email delivery and affect your reputation as a sender. Even though these filters are usually accurate, they can mistakenly block legitimate emails.

Several factors can lead to this issue —

  • Lack of proper email authentication is a common cause. Ensure you have set up DKIM, SPF, and DMARC correctly. Also, check your PTR Records to see if they align with the A record in your domain’s DNS.
  • ISPs consider user behavior in their filtering decisions. If you send emails that no one opens, the server might start blocking them to prevent cluttering inboxes. It’s a good idea to regularly clean your email list and remove contacts who don’t engage with your emails.

What Can You Do?

For bounces from smaller domains, try contacting the ISP directly to resolve the issue. Also, reach out to our Support Team for assistance with larger domains. They can help improve your email deliverability and reduce the chances of your emails ending up in spam.

How to Improve Your Email Bounce Rate

How to Improve Your Email Bounce Rate

Keeping track of your email bounce rate is useful, but it’s crucial to tackle the reasons behind a high rate. Here’s a straightforward strategy to help you reduce it —

1. Implement Double Opt-In for New Subscribers

The double opt-in method involves two steps. First, someone signs up with their email on your site. Then, they get an email with a verification link. They only join your list after clicking this link.

Although it might slow down how fast your list grows, double opt-in ensures that people really want your emails. It leads to fewer bounced emails and a list of subscribers who are more interested in what you send.

By using double opt-in, you’re likely to see a better email delivery rate, reducing issues like hard bounce email and soft bounce Mailchimp problems.

2. Use a Professional Email Service

Avoid sending marketing emails from free services like Gmail because —

  • It can appear unprofessional and negatively impact your brand.
  • Free email services often fail to meet DMARC policies, increasing the risk of hard bounce email issues. 
  • Use a custom email address for a more professional approach and better email delivery.

3. Regularly Clean Your Email List

High email bounce rates often occur when your list is outdated. Over time, many subscribers change their email addresses. It’s important to —

  • Regularly check and update your list. Remove wrong addresses caused by typos or errors.
  • Periodically review feedback and unsubscribe people who mark your emails as spam or complain.
  • Actively remove subscribers who don’t open your emails. While it might seem odd to remove people, it’s better to have a list of active, interested subscribers.

4. Make Sure Your Domain is Verified

Using DMARC, SPF, and DKIM, which are key methods to verify your domain. Surprisingly, less than 40% of companies complete this process.

Verifying your domain can reduce your email bounce rate and make sure more of your emails are delivered successfully. It also stops security warnings from showing up for your subscribers when they open your emails. 

This step is important for maintaining a healthy balance between soft vs hard bounce email rates.

5. Email Your List Regularly

To keep your bounce rate low, it’s important to email your subscribers often. If people sign up and then don’t hear from you for a long time, they might forget they subscribed and think your emails are spam.

Aim to send emails at least once a week. This keeps your subscribers interested and helps build a strong relationship with them. In addition to managing bounces, learning how to find someone’s email on LinkedIn can make your email marketing campaigns more effective.

6. Personalize Your Emails by Segmenting Your List

Just having an email list isn’t enough. You need to understand your audience and send them content they find interesting and relevant. Personalized emails are much more effective than general ones. Here’s how to do it —

  • Divide your subscribers into groups based on things like where they live, what they like, and what they need.
  • Then, send tailored emails to each group. 

Besides, an Experian study found that emails tailored to the individual are six times more successful than standard, one-size-fits-all emails. Not only does this approach improve engagement, but it also lowers email soft bounce rates, since personalized content is less likely to be ignored.

7. Use Clear Language in Emails

Be careful with the words you choose in your emails. Sometimes, without knowing it, you might use words that email providers see as spam. This can send your emails directly to the junk folder. Avoid phrases like 

  • 50% off
  • Free offer
  • Drastically reduced
  • Act now
  • Make money

Also, using too many dollar signs can make your email look like spam. To effectively reduce your email bounce rates, exploring creative ways to reach prospects ensures your messages land in the right inboxes.

8. Keep Track of Your Email Performance

It’s important to regularly check how well your email campaigns are doing. Just because they’re effective now doesn’t mean they’ll always be. By continuously monitoring your email deliverability, you can stay ahead —

  • Regularly test different versions of your emails (A/B testing) to see what your subscribers like best.
  • Watch your email bounce rates, how many people open your emails, and feedback like spam complaints.
  • By keeping an eye on these details, you can catch and fix small issues before they become bigger problems.

9. Implement a Preference Center for Subscribers

As your email list gets bigger, it becomes more challenging to keep subscriber information current. This is where a preference center can be very useful. It’s a tool in your emails where subscribers can —

  • Update their personal details like their email address.
  • Choose how often they want to hear from you.
  • Opt out of emails if they wish.

You can also offer more detailed options, like letting subscribers set their interests. This way, your data stays accurate, and your subscribers have more control over what they receive from you.

Email Marketing with Swordfish AI: Reducing Bounce Rates

Email Marketing with Swordfish AI

Swordfish AI is a groundbreaking contact finding tool for email marketers. Unlike typical platforms, we reshape how marketers handle email campaigns.

Our standout feature is a unique cell phone number database with a special verification system. It’s great for cold calling, ensuring messages reach the right people. Accurate contact details mean fewer emails go to wrong or non-existent addresses, cutting down on hard bounces.

Swordfish AI also offers access to a massive pool of over 3.5 billion profiles of data. It allows for more targeted and personalized emails, increasing engagement and reducing spam reports. 

We help you to keep your email lists clean and up-to-date, avoiding soft bounces caused by issues like full inboxes.

Features of Swordfish AI

Swordfish AI has several features that help with reducing email bounces —

  • Prospector Tool

Prospector Tool

The Prospector is designed to help you create specific lists for calls or emails quickly and accurately. It uses advanced filters to streamline the process of finding new leads.

  • Chrome Extension for Gathering Data

Chrome Extension for Gathering Data

There’s a Chrome extension with Swordfish AI. It lets you easily collect contact info from websites and social media, which is handy for marketers gathering data online.

  • API Integration

API Integration

Swordfish AI can be integrated with CRM systems. This makes updating contact lists easier and helps marketing teams work smoothly.

  • Follows Privacy Rules

The platform sticks to GDPR and CCPA rules. This means marketers can use it without worrying about breaking privacy and security laws.

arrowTry Swordfish Ai


You can avoid blacklists, stay off blacklists, and keep your emails in inboxes by understanding soft bounce vs hard bounce email. So, you get a bounce notification, it’s important to see if it’s a soft or hard bounce. 

They mean different things for your emails. Now, you know how to tell them apart and deal with them. 

Soft bounces are usually short-term problems and often fix themselves over time. Hard bounces are more serious and need you to take action. If you don’t handle bounces right, your sender score could drop.

Remember, having a good process for handling bounces is a big part of email marketing. Make your email campaigns easier with Swordfish AI. Our tools help you manage email lists up to date and improve your sender score, keeping your emails away from spam. 

Start using Swordfish AI today and improve your email marketing!

arrowTry Swordfish Ai


What do bounce codes mean?

Bounce codes are three-digit numbers starting with 4 or 5. They tell you if a bounce is temporary (soft) or permanent (hard). For instance, codes starting with 4 indicate a temporary issue, like a full mailbox or a server problem.

How can I differentiate between a hard bounce and a soft bounce?

If you’re using an ESP, it will automatically tell you whether a bounce is hard or soft and why the email wasn’t delivered. If you’re sending emails yourself, you’ll need to look at the SMTP reply from the recipient’s server to understand the type of bounce.

Should I delete hard bounce emails?

When you find out an email has bounced, it’s a good idea to delete that email address from your list right away. Hard bounces are permanent problems, so removing these email addresses quickly is the best approach.

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