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

Email marketing is one of the strongest digital marketing tools for businesses to connect with their customers, nurture leads, and drive conversions. However, a common challenge every marketer faces occasionally is email bounces. 

When your email fails to reach the recipient’s inbox, it bounces back to the sender, but not all bounces are the same. Some bounces are temporary, while others are irreversible. 

If you want to maintain a healthy email list, you need to understand the difference between hard and soft bounces so that you can improve its deliverability and protect your sender reputation. 

In this blog post, you’ll learn about the email bounce rates, the difference between hard and soft bounces, and some tips to reduce bounce rates in your email campaigns. 

What is an Email Bounce?

An email bounce occurs when an email message isn’t delivered to the recipient’s email server. And instead of reaching the recipient’s inbox, the message is returned to the sender with a notification about the cause of the failed delivery. 

The main causes of email bounces are technical difficulties, invalid email addresses, or restrictions set by the recipient’s email server. 

There are two main types of email bounces: hard bounce and soft bounce. A hard bounce is a permanent delivery failure, while a soft bounce is a temporary delivery issue with email. 

When email marketers understand the cause of the failed delivery and assess the issue, they can decide whether to retry sending the email or remove the address from their list. There are multiple tools used by email marketers and other email service providers (ESPs) to check email bounce rates.

What is a Hard Bounce?

A hard bounce occurs when an email can’t be delivered due to a permanent issue. This means the message will never reach the recipient, no matter how many times you try to send it. 

Hard bounces are often caused by invalid or non-existent email addresses. Because these addresses can’t receive emails, they should be removed from your mailing list as soon as possible. 

Common Causes of Hard Bounces

Hard bounces can occur due to multiple reasons, and some of the most common reasons are given below: 

1. Invalid Email Address

When there is any invalid email address in your mailing list, it won’t reach the recipient’s inbox and will be returned to the sender. It might be possible that the email address you added to the list may contain a typo or simply doesn’t exist.

2. Non-existent Domain

If there is any domain name after the “@” symbol that is invalid or no longer active, there are more chances of a hard bounce. 

3. Recipient Server Blocking the Email

Some servers permanently block certain domains or IP addresses due to security or spam concerns. This leads to a hard bounce of your email. 

4. Authentication Failure

Your email may fail authentication checks like SPF, DKIM, or DMARC, which can cause the server to permanently reject it. It can also result in high spam rates and damage the deliverability. The main causes of authentication failure include incorrect DNS records, outdated security protocols, or expired credentials. 

Why Hard Bounces Are Dangerous

Hard bounces are dangerous because they can seriously damage your sender’s reputation and deliverability due to containing invalid or non-existent email addresses. 

High hard bounce rates (ideally kept below 0.5%–1%) can cause ISPs and spam filters to flag your domain as a spammer, which leads to blocked emails and lower inbox placement. In some cases, this also leads to account suspension by email service providers. 

Email providers like Gmail, Yahoo, and Outlook monitor bounce rates closely. If there are too many bounced emails, they may start treating your messages as suspicious. That’s why email marketers should remove hard-bounced email addresses immediately from their mailing lists.

What is a Soft Bounce?

A soft bounce occurs when an email is not delivered due to a temporary issue like a full inbox, server downtime, or a large message size. Unlike hard bounces, soft bounces usually resolve on their own. 

Since these addresses are valid, they often do not require immediate removal from your mailing list. In most cases, email service providers automatically try to resend the message after some time. However, persistent soft bounces may convert into hard bounces. 

Common Causes of Soft Bounces

There are many reasons behind soft bounces, but they are all temporary, and some common causes of soft bounce email delivery are given below:

1. Mailbox is full

While sending bulk emails to your mailing list, some recipients’ inboxes have reached their storage limits, so they can’t receive new messages, which causes the emails to bounce back to the sender. This is also one of the common causes of soft bounce email. 

2. Temporary Server Problems

Sometimes the recipient’s email server may be experiencing issues, such as being offline or overloaded, which can also cause a soft bounce. 

3. Email Size Too Large

When sending bulk emails, expert email marketers suggest that if your attachments or images make the email too large for the recipient’s server, it will lead to a soft bounce.

4. Spam Filters or Security Checks

One common reason for a soft bounce rate may be a greylisted or blocked email address. In this case, the email is temporarily blocked due to spam filters, content, or rate limits.  

5. Temporary Domain Issues

A soft bounce can also be caused by configuration problems or outages on the domain server. 

What Happens After a Soft Bounce?

Most email platforms automatically retry sending the email several times. If the message continues to fail after multiple attempts, the system might classify it as a hard bounce. That’s why frequent soft bounces should also be tracked carefully, suggest digital marketing experts.

Hard Bounce vs. Soft Bounce: Key Differences

The main difference between a hard bounce and a soft bounce is whether the delivery is permanent or temporary. In hard-bounce emails, no retries are possible, and the impact is highly negative. On the other hand, in soft bounces, an automatic retry is possible, and the impact on the sender’s reputation is moderate. 

In a hard bounce, you need to remove the address immediately; in a soft bounce, you need to monitor and retry sending the emails. In simple terms, hard bounce email rates are permanent, and soft bounces are a temporary problem. Understanding these factors and the difference between them can help you manage your email list more effectively. 

How to Reduce Email Bounce Rates

While email bounces can’t be completely avoided, here are some tips to reduce email bounce rates in your email campaigns: 

1. Use double opt-in, which helps your subscribers to confirm their email address before joining your list. 

2. Regularly remove the inactive or invalid email addresses to keep your list healthy and improve deliverability. 

3. Authenticate your email domain so that it can prove to mailbox providers that you’re a legitimate sender. This improves trust and reduces the risk of bounces. 

4. You need to avoid spam-like content because clean, organized content performs well. Certain content elements, like excessive capitalization, misleading subject lines, and large attachments, can trigger spam filters and cause delivery issues. 

5. Segment your email list by demographics, purchase behaviors, interests, and engagement history to send relevant content to the right audience. It will further increase engagement and reduce spam complaints. 

Final Thoughts

Most email platforms provide analytics showing the hard bounce rate, soft bounce rate, total bounce percentage, and specific bounce reasons. These insights help email marketers to identify the problem early and improve campaign performance.  

For an effective email marketing campaign, you need to know the difference between soft bounces and hard bounce rates, whether you’re an email marketer or just started using ESPs like TrueSend. 

Businesses can ensure their messages consistently reach their target audience by maintaining a clean email list, following proper email marketing tactics, and using trusted platforms to manage their email campaigns. 

Want to boost your deliverability rates and decrease the email bounce rates? Let us help you achieve it by creating a free TrueSend account to enhance your email campaign with double opt-in features, email list hygiene tools, delivery analytics, and many more.