7 Ways to handle email bounces

Email marketing remains one of the most powerful tools for driving engagement, building relationships, and generating revenue. However, there is one major challenge that can derail even the most well-planned campaigns: email bounces. When your emails fail to reach the intended recipient’s inbox, it not only reduces engagement but also harms your sender reputation, affects deliverability, and ultimately impacts your return on investment.

This guide provides a detailed explanation of what email bounces are, why they happen, the types of bounces, and actionable strategies to fix and prevent them.

What Is An Email Bounce?

An email bounce occurs when the email you send fails to reach the recipient's inbox and is instead bounced back to you. In the digital world, this typically means that the recipient's MX server rejected the email for one reason or another.

Frequent email bounces often indicate deeper issues, such as poor list hygiene, missing authentication, or content filters flagging your emails as suspicious. And when those issues add up, they don't just waste your effort; they can harm your sender reputation and make future campaigns less effective, making it harder for even valid emails to reach the inbox.

Understanding the types of email bounces is the first step toward maintaining effective campaigns and a strong reputation.

Types Of Email Bounces

Email bounces fall into two main categories: Soft bounces and Hard bounces.

Soft Bounce

A soft bounce is a temporary delivery failure. It means your email address was valid, but the message couldn't be delivered at that moment. Common reasons include the recipient's inbox being full, the mail server being down, or the message being too large to process.

Let's take an example: You run a holiday promotion for your e-commerce store and send an email campaign to thousands of subscribers. One customer, Maria, has a valid Gmail address, but her inbox is full. Your message to Maria bounces back as a soft bounce. The good news is that once Maria clears out her inbox, future emails can go through without any changes on your part.

In some cases, the recipient's mail server will greylist the message, which means it temporarily rejects your email the first time it’s received. If your mail server retries after a short delay, the recipient’s mail server will usually accept the message the second time.

Soft bounces don't always require immediate action, but monitoring them is crucial.

Hard Bounce

A hard bounce, on the other hand, is a permanent email bounce. It means the email address is invalid, the domain doesn't exist, or the receiving mail server has blocked delivery. Unlike soft bounces, hard bounces will not resolve themselves, and continuing to send to those addresses can damage your reputation.

For instance, when hosting a webinar, you can collect sign-ups through a form. One attendee mistypes their email as "johndoe@gmial.com" instead of "gmail.com." When you send a follow-up campaign, the message bounces back immediately because the domain is invalid. That's a hard bounce.

Another example is that a subscriber signs up using maria@domain.com instead of domain maria@domain.comm (extra “m”). The domain is invalid, which prevents mail servers from being found, resulting in a hard bounce.

Hard bounces require immediate attention because they indicate a permanent issue. These email addresses should be removed or corrected right away to maintain a healthy sender reputation and ensure better deliverability for future campaigns.

Why Do Emails Bounce?

There are several reasons why an email might bounce, ranging from simple typos to more complex issues with deliverability. Let’s break down some of the most common causes.

Invalid Or Mistyped Addresses

One of the most straightforward reasons for a bounce is that the email address doesn’t exist. Typos, such as “yaho.com” instead of “yahoo.com”, are common. In other cases, the address may have been abandoned or deleted. For instance, if an employee leaves a company, their corporate email account might be deactivated, resulting in a hard bounce.

Full Mailbox

A classic reason for a soft bounce is when the recipient’s inbox is full. Although many modern email providers offer ample storage, issues persist, particularly with older or less frequently checked accounts. A subscriber who hasn’t logged in for months may unknowingly cause your email to bounce until they clear space.

Server Issues

Sometimes the problem lies with the recipient’s mail server. If it’s down for maintenance or experiencing high traffic, it may temporarily reject incoming emails. These are usually soft bounces and often resolve once the server is back online.

Email Size Too Large

Emails with heavy graphics, large attachments, or bloated HTML can exceed the size limits set by receiving servers. For example, if you send a high-resolution catalog as an attachment, some recipients’ servers may block it, leading to a bounce.

Authentication Failures

If your domain isn’t authenticated with SPF, DKIM, and DMARC, ISPs may not trust your messages. Without these protocols, your emails can be mistaken for spam or phishing attempts, resulting in rejections or bounces even to valid addresses.

Content Triggers

Sometimes the issue lies in the content itself. Spammy subject lines filled with capital letters, excessive exclamation marks, or misleading claims can set off filters. The server might reject the email to protect the recipient, causing a bounce.

Blacklisted IP Or Domain

If your IP address or domain has been blacklisted due to spam complaints or poor sending practices, many servers will automatically block your emails. This is a serious issue that can lead to widespread hard bounces until the reputation problem is resolved.

Policy Blocks

Some organizations block external emails by default for security reasons. For example, a company might configure its mail servers to reject all outside newsletters unless they are explicitly allowed. In such cases, your message will bounce even though the address itself is valid.

7 Ways To Solve Email Bounces

Nothing is more frustrating than seeing your carefully crafted email messages bounce back. A bounce isn’t just a technical hiccup; it’s a sign that something in your campaign process needs attention, whether it’s your list quality, domain setup, or spam triggers. The good news is that bounces are preventable.

We’ll explore the seven steps to solve the problem effectively.

1. Verify Email Addresses Before Sending

The first and most critical step to reducing email bounces is verifying addresses before you hit send. When you send emails to undeliverable or inactive addresses, it's like mailing letters to homes that no longer exist; the message will come right back. That bounce not only wastes your effort but also damages your sender's reputation over time, making it harder for future campaigns to reach inboxes.

By running your list through an email verification tool like Emailable before sending, you filter out invalid email addresses.

Let's consider a scenario: a retail brand has 50,000 subscribers and decides to clean its list before launching a holiday campaign. The verification process removes 20,000 invalid email addresses, ensuring the campaign only goes to real, active inboxes. The result will be fewer bounces, stronger engagement, and a better domain reputation. This preparation pays off in the long run, because email providers like Gmail and Outlook reward senders who consistently maintain low bounce rates.

Verifying your list isn't just housekeeping; it's a safeguard that protects your deliverability and keeps your campaigns performing at their best. It's the foundation on which every other step builds.

2. Authenticate Your Domain (SPF, DKIM, DMARC)

Authenticating your domain is one of the most effective ways to protect your emails from being flagged as spam. Internet service providers (ISPs) require proof that the message originates from you, not a scammer pretending to be your brand. That’s where SPF, DKIM, and DMARC records come in. They act like ID checks for your emails, confirming that the sender is authorized and the message hasn’t been tampered with.

Here’s how it works in practice. SPF (Sender Policy Framework) informs mail servers which IP addresses are authorized to send emails on behalf of your domain. DKIM (DomainKeys Identified Mail) adds a digital signature to your messages, allowing the receiving server to verify that they haven’t been altered during transit. DMARC (Domain-based Message Authentication, Reporting, and Conformance) ties together SPF and DKIM, allowing you to define what should happen if an email fails these checks, whether it’s rejected, flagged, or sent to spam.

Imagine you run a SaaS company sending invoices from billing@yourdomain.com. Without proper authentication, Gmail, Outlook, or any MX providers might not trust the messages and block them, resulting in bounces. But once you set up SPF, DKIM, and DMARC, the MX providers can verify the email’s authenticity and deliver it straight to the inbox. Over time, this improves your domain’s reputation, reduces false bounces, and makes ISPs more confident in letting your email campaigns through.

Think of authentication as putting locks and seals on your outgoing mail. It reassures providers and recipients that the message is legitimate, thereby maintaining strong deliverability.

3. Use A Professional & Reputable Sender Domain

Using a professional and reputable sender domain is essential if you want your emails to be trusted by inbox providers and your audience. Free domains like Gmail, Yahoo, or Outlook might work for personal communication, but when you send marketing or transactional emails from them, ISPs often treat those messages with suspicion. They know that legitimate businesses usually invest in their own domain, so sending from a free address can trigger spam filters or result in outright bounces.

Another advantage of using your own domain is consistency. Over time, inbox providers evaluate your sending reputation. If you consistently send valuable, permission-based emails from the same domain, your reputation improves and your messages are more likely to land in the inbox. This reputation can’t be built with a free email provider.

Think of your sender domain as your digital storefront. A free address is like selling from a temporary stall, while a branded domain is like welcoming customers into a store with your name on the sign. The difference is trust, and trust is what keeps your emails from bouncing.

4. Maintain A Healthy Sender Reputation

Your sender reputation is like a credit score for your email domain and IP address. Internet service providers (ISPs) use it to decide whether to deliver your messages to the inbox, send them to spam, or block them altogether. A poor reputation often leads to more bounces, while a strong one helps ensure consistent deliverability.

Maintaining a healthy sender reputation starts with responsible sending practices. This means avoiding purchased lists, sending emails only to people who have opted in, and regularly cleaning your database. It also means paying attention to engagement signals, such as opens, clicks, replies, and even unsubscribes. ISPs track these behaviors to gauge how recipients feel about your emails. If too many people ignore or mark your emails as spam, your reputation suffers.

Your reputation isn't built overnight, but every campaign contributes to shaping it. By keeping your lists clean, sending content that your audience values, and adhering to best practices, you protect your standing with ISPs. A healthy reputation is the key to fewer bounces and more reliable inbox placement.

5. Optimize Email Content & Avoid Spam Triggers

The content of your email significantly affects whether it gets delivered or bounces back. Internet service providers (ISPs) and spam filters analyze every message you send. Suppose your content appears suspicious, such as using excessive capital letters, too many exclamation points, or spammy words like “FREE!!!” or “GUARANTEED”. In that case, your email is more likely to be flagged and blocked. That rejection can be considered a soft bounce, and repeated issues may harm your domain’s reputation over time.

Optimizing your content means striking the right balance between creativity and compliance. Keep subject lines clear and professional, avoid deceptive language, and make sure your HTML is clean. If your email is poorly coded, missing alt text for images, or has an image-to-text ratio that’s too heavy on visuals, filters might reject it. Adding a clear unsubscribe option also shows ISPs that you respect recipient preferences, which works in your favor.

6. Monitor And Remove Hard Bounces Regularly

Hard bounces are a clear signal that an email address is invalid or no longer active, and continuing to send to those addresses can seriously damage your deliverability. Internet service providers (ISPs) see repeated attempts to reach bad addresses as a sign of careless sending behavior, which can lower your sender reputation and cause even valid messages to be blocked. That’s why it’s essential to monitor and remove hard bounces regularly from your list.

A hard bounce typically happens when an address doesn’t exist, the domain is incorrect, or the recipient’s server has permanently blocked delivery. Unlike soft bounces, which may resolve themselves (like a full inbox), hard bounces are permanent. If you don’t clean them out, you’re wasting time and risking your credibility with ISPs.

Treat bounce monitoring as routine maintenance. By regularly reviewing reports and removing addresses that cause hard bounces, you protect your sender reputation and keep your campaigns running smoothly. It’s a simple habit that pays off with better inbox placement.

7. Track & Improve Deliverability Continuously

Deliverability isn’t something you fix once and forget; it’s an ongoing process that requires constant tracking and improvement. MX providers and ISPs frequently adjust their filters, and subscriber behavior changes over time. Even minor issues with your list or content can impact whether your emails reach the inbox. By closely monitoring your deliverability metrics, you can identify problems early and adapt before they become costly bounce issues.

Key metrics to monitor include bounce rates, open rates, click-through rates, spam complaints, and inbox placement tests. If you notice an unusual spike in bounces, it may indicate a problem with list quality. If open rates suddenly drop, your subject lines or sender reputation may need attention. Using tools that provide real-time deliverability insights helps you understand how ISPs view your campaigns and identify the necessary adjustments.

Continuous tracking is like having a dashboard for your email program; it shows you where things are running smoothly and where maintenance is needed. By measuring performance and making minor, consistent improvements, you build resilience against bounces and keep your campaigns reliably landing in inboxes.

Conclusion

In short, tackling email bounces isn’t just about fixing errors. It’s about safeguarding your ability to communicate. Every bounced email that could have reached an engaged subscriber represents a lost opportunity.

Verifying addresses, authenticating your domain, using a trusted sender identity, maintaining a good reputation, optimizing content, clearing out hard bounces, and keeping a watchful eye on performance are your blueprint for consistent success.

Consider these practices as the foundation of strong deliverability. When your list is clean, your setup is verified, and your content respects both recipients and filters, ISPs begin to reward that effort. Over time, fewer bounces result in stronger sender credibility, improved inbox placement, and campaign performance.

Do the work now, keep refining, and your email marketing will no longer be held back by what used to bounce.