Overview
Bounced emails can hurt your deliverability and make it harder to reach your audience.
A bounced email means your message couldn’t be delivered to the recipient’s inbox. In Apollo, bounces usually fall into two types: soft bounces caused by temporary issues like a full inbox or server error, and hard bounces caused by permanent problems like an invalid email address. Too many bounces can damage your sender reputation, lower deliverability, and reduce your chances of getting replies.
By understanding why emails bounce, you can catch problems early, clean your data, and protect your email performance.
Check out the following guide to troubleshoot bounced emails.
Soft vs Hard Bounce
There are two types of email bounces:
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Soft bounce |
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Cause
With a soft bounce, a temporary issue prevents your email from arriving in the intended inbox. Reasons can include:
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Solution
Review your content. Some servers might reject emails with large attachments or spammy formatting. Check Email Deliverability Best Practices for formatting tips. If you’re using a third-party email provider like SendGrid or Mailgun, review your email logs there for more detail. Most soft bounces resolve on their own, so waiting and retrying is often enough. However, if the same contact continues to bounce, consider removing or replacing the address to protect your sender reputation. |
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Hard bounce |
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Cause
With a hard bounce, a permanent issue prevents your email from arriving in the intended inbox. Reasons include:
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Solution
Double-check for typos in the email address. Many hard bounces are simply the result of a misspelling. If the address came from a third-party source, it may be outdated or inaccurate. Apollo automatically blocks emailing hard-bounced addresses, so you won’t accidentally keep sending to them. Remove the address from your list. Continuing to send to hard-bounced contacts will damage your sender reputation. |
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If your email lands in the recipient's spam folder, the recipient can still view the email if they wish to. Therefore, this doesn't count as a bounce. A bounce means the message couldn’t be delivered to the recipient’s inbox at all.
When an email hard bounces it can damage your email domain reputation. If you consistently notice a bounce rate more than 10% across all your sequences, there could be several potential reasons and solutions.
Reasons For a High Bounce Rate
If you're seeing a high bounce rate in Apollo, there could be a few factors at play. Click each factor to learn more and how to fix it:
| Using third-party verification services | Emailing unverified email addresses |
| Emailing spam-blocked email addresses | Email addresses provided by other tools |
| Natural email quality decay |
Using third-party verification services
Apollo has a robust algorithm for detecting valid email addresses. Often, this algorithm is more powerful than other third-party services like NeverBounce or ZeroBounce. Third-party verification tools may reject many valid emails as catch-all or unknown. If you're using one of these tools, consider using Apollo as your verification tool.
For more information about email verification, check out How Apollo Verifies Emails.
Emailing unverified email addresses
If you enroll contacts with an unverified or update required email status in your sequences, your emails have a higher chance of bouncing. Apollo strongly recommends that you only enroll contacts with verified or likely to engage email addresses into your sequences. When Apollo detects a hard bounce, Apollo automatically removes the email address from contacts to prevent further outreach. However, if you import a contact with the same email address from a CSV or CRM, you can still email them. In this case, Apollo recognizes it could result in a likely bounce, causing the email to not be sent.
Emailing spam-blocked email addresses
Apollo offers comprehensive reporting about all of the emails you send through Apollo. This includes reporting specifically related to emails that bounce as a result of spam blocking.
To access reporting for spam blocked emails:
- Launch Apollo and click Emails.
- Set the status filter to Spam Blocked.
Check out View and Respond to Emails to learn more about managing emails on Apollo.
The mailbox provider has blocked the email if it has a spam blocked status in Apollo. Reasons can include:
- Domain reputation
- Excessive send frequency
- Lack of personalization and other content bad practices.
To learn how to avoid having your email spam blocked, check out Avoid Spam Filters.
If you notice that a large number of emails sent around the same time have been spam blocked, you need to act fast and make changes to your email approach. Follow the best practices in the email deliverability checklist to keep your domain reputation safe and improve your email deliverability with Apollo.
Email addresses provided by other tools
As an all-in-one lead generation and engagement tool, Apollo allows you to send emails to existing contacts from your CRM like Salesforce or HubSpot or CSV uploads. Apollo cannot guarantee the accuracy of email addresses provided by other third-party tools or sources.
If you want to check a specific contact to see if Apollo provided their email address, search for that contact or browse directly to their profile from a sent email.
Scroll to Activities on the contact's profile and look for a message that says:
Apollo's automatic email fulfillment found a verified email [email@domain.com] for [Contact Name].
If Apollo enriched a contact with a verified email address and charged you a credit, you can view a log of the activity.
To access the data request history:
- Launch Apollo and click Settings > System activity > Data requests.
- Apollo shows all data enrichment requests. You can see the number of contact emails requested versus the number of credits charged for verified emails in each request.
- Click a specific request to view the contact information you requested.
For more information about how data requests work in Apollo, check out How Do Data Requests Work?. If you want to learn more about Apollo credits in general, refer to What Are Credits?.
Natural email quality decay
Email addresses are living entities. People may use them for some time and then may abandon them for any number of reasons, such as moving to a different job with a new email address. With this in mind, if Apollo provided you with a verified email address more than 6 months ago, we do not provide the same level of bounce rate guarantee. Contacts with verified email addresses older than 6 months may need additional enrichment.
FAQs
| Frequently asked questions | ||
|---|---|---|
| Why did my email bounce? | What is an acceptable bounce rate, and when should I be worried? | Should I remove or never email contacts that bounced? |
| How does Apollo verify emails, and do I still need third-party verification? | Do bounced emails affect my domain’s reputation? | Can I see which contacts bounced in Apollo? |
Why did my email bounce?
An email bounces when it can't be delivered to the recipient. In Apollo, bounces are classified as either soft or hard. Soft bounces are caused by temporary issues such as a full inbox or a server error and may be resolved. Hard bounces are caused by permanent problems such as an invalid email address and usually cannot be resolved.
To find the specific reason an email bounced:
- Launch Apollo and navigate to Emails.
- Click Show filters, and set the status filter to Bounced.
- Click the bounced contact and view the activity feed for more details on what went wrong.
What is an acceptable bounce rate, and when should I be worried?
In an ideal world, you would have 0 bounced emails, but the reality is that some bounces are unavoidable. An acceptable bounce rate is typically under 2%. Anything higher can signal problems with your data quality, targeting, or email setup. If your bounce rate consistently exceeds 5%, you should investigate immediately. High bounce rates can damage your domain reputation and lead to your emails being flagged as spam or blocked entirely. Always follow email deliverability best practices to protect your domain, and regularly monitor your mailbox's deliverability score.
Should I remove or never email contacts that bounced?
You don’t need to remove every contact after a bounce. What matters is the type of bounce. For soft bounces, it’s fine to retry since the issue is usually temporary. But if the same contact bounces multiple times, it’s safer to stop emailing them. For hard bounces, you should stop sending immediately. Apollo automatically suppresses hard-bounced contacts to protect your sender reputation, but you can also remove or replace them in your lists to keep your data clean.
How does Apollo verify emails, and do I still need third-party verification?
Apollo has a built-in email verification process with a 91% accuracy rate, and unlike most vendors, Apollo doesn't rely solely on SMTP tickling to validate emails. Apollo's 7-step email verification process can differentiate between valid and invalid emails for both catch-alls and solo inboxes. For this reason, you don't need a third-party email verification service. Learn more about how Apollo verifies emails.
Do bounced emails affect my domain’s reputation?
Yes, bounced emails can hurt your domain’s reputation. Hard bounces in particular signal permanent delivery failures, and mailbox providers track those signals when calculating your sender score. If your hard bounce rate climbs too high, providers may start flagging or blocking your messages as spam. Soft bounces generally don’t damage your reputation as deeply unless they recur from the same address. Apollo’s deliverability score includes bounce rates as a key metric. If you see your score dip, it’s a warning sign to investigate and resolve any bounces.
Can I see which contacts bounced in Apollo?
Yes, you can. Apollo surfaces bounced contacts in a couple of places so you can take action right away:
- Sequences: Open any sequence and click the Bounced metric to see each contact whose email has bounced. Learn more.
- Emails: Set the status filter to Bounced. Apollo shows each contact whose email has bounced. Learn more.
Next Steps
Use these tools to strengthen your email performance and stay on track with outreach.
| Email Deliverability Best Practices | Learn how to improve deliverability, avoid spam folders, and increase response rates. Apollo's guide covers domain setup, sending behavior, and writing emails that sound human and authentic. |
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| Troubleshoot Sending Emails | Diagnose send failures and understand not-sent reasons with Apollo’s troubleshooting guide. Learn how to interpret error codes, review integration logs for SendGrid or Mailgun, and resolve delivery issues quickly to keep your outreach on track. |
| Use Email Warmup | Use email warmup or inbox ramp up to help build a positive sender reputation and signal to mailbox providers that your emails are safe and trustworthy. Email warmup is best for brand new domains and mailboxes. Inbox ramp up is best for existing mailboxes and domains with prior sending history. |
| Monitor the Deliverability Score of a Connected Mailbox | Track your mailbox health metrics like bounce rate, spam rate, and click rate, and drill into any issues flagged by Apollo. |
| Email Deliverability Webinar | Watch Apollo's Email Deliverability 101 webinar to learn deliverability do’s and don’ts directly from sales experts. This webinar includes real-world sending strategies and audience Q&A. |