What is a bounce and how can I prevent them?


This article explains what a bounce is and how it occurs. It also explains why this is important for your deliverability.

What is a bounce?

If you have an automation that sends 100 messages to various contacts, each takes a unique path to the inbox. For example, you have an automation that sends a message to Joe at Gmail (joe@gmail.com). This is the technical conversation that happens when we attempt to deliver that message:

ActiveCampaign: Hello, Gmail
Gmail: Hi
ActiveCampaign: We have a message for Joe
Gmail: Okay, great, give us that message, and we'll pass it along to Joe!

That whole conversation only takes a few milliseconds, but it's essential to understand because sometimes things don't go smoothly. This is what the conversation would look like if I try to send a message to an address at Gmail that doesn't exist, say bill@gmail.com:

ActiveCampaign: Hello, Gmail
Gmail: Hi
ActiveCampaign: We have a message for Bill
Gmail: Bill doesn't have a Gmail account. That account doesn't exist. Goodbye.

In this case, Gmail told us the email address didn't exist. Maybe Bill closed his account. Perhaps it never existed in the first place. This is a bounce.

Why are bounces important?

Bounces are significant for deliverability because a sender that routinely has a high bounce rate is most likely using old lists. If you regularly send messages to invalid accounts that bounce, inbox providers like Gmail will consider your email "risky" and begin to send it to the spam folder.

Don't worry; we have you covered here. Whenever a contact hard bounces, they are marked as "bounced" and is automatically stopped from getting more messages.

You can learn about contact statuses and what it means if their email address bounces.

Why are my messages bouncing?

These are the most common reasons a message might bounce:

  • The address doesn't exist (Hard Bounce)
    These types of bounces have a bounce code that begins with 5xx. It's normal to have a handful of these on every send because inbox providers shut down accounts that haven't been used for years.
  • Temporary bounce (Soft Bounce)
    These bounces have a bounce code that begins with 4xx or 5xx. Many temporary errors, like a full mailbox or a brief server outage at the inbox provider, can occur. If we get three temporary bounces in a row for any particular contact, we will mark the contact as "bounced" as if they had hard bounced.
  • Reputation
    If you receive many spam complaints, certain inbox providers may block your email based on your poor sending reputation.
  • Message content
    If your message contains a phrase, blocklisted link, bad image, or link to a site with malware, inbox providers will bounce this message.
  • You may not have set up authentication
    As of February 2024, Gmail and Yahoo are requiring all senders to set up DKIM and DMARC for all domains. If you have not set up authentication, it can lead to bounces due to these changes. Learn how to set up your sending domain to set up your authentication, which includes DKIM and DMARC.
    Also, here is a helpful article about the most common DKIM mistakes to learn more.
  • Something is wrong with your public DKIM key
    You should check the Most Common DKIM mistakes.
  • Restrictive DMARC record for your sending domain
    This can cause legitimate messages to bounce. You can use a DMARC Record Check tool to check your DMARC record. Having a p=reject record will cause all messages to bounce if you haven't set up DKIM. In ActiveCampaign, you set up DKIM when you set up your sending domain. Learn how to set up your sending domain 
  • "From email" address
    If you are sending with a "From email" address you are not allowed to use (like @yahoo.com or @chasebank.com), this will cause the message to bounce.
  • "Auto-bounce" bad email addresses
    We "auto-bounce" some contacts that are bad addresses, like 12345678910@12345.com. These contacts appear in the message report as "bounced" with a 9.1.5 bounce code because we identified it as a bad address.

I see a spike in my bounce rate. What happened?

Usually, this means that you somehow introduced a list of contacts that haven't been sent emails recently and contained a lot of old, inactive email addresses that no longer exist. You should take a hard look at the lists you used to ensure you didn't accidentally add in some old contacts who shouldn't be there.

It can also happen if your message contains a phrase or link that triggered certain major spam filters. In future campaigns, you can fix this temporary issue by avoiding that phrase or link.

Lastly, there is a chance that the spike is due to a block because of high spam complaints. These usually resolve themselves if you don't have a history of high complaint rates.

How can I reduce my high bounce rate?

As long as you only use healthy data collection practices (secure opt-in forms), you will see a low bounce rate.

Some addresses on your list may shut down and bounce due to natural list churn. Some people may sign up with a misspelled address (like joe@gmai.com). It's normal to see 0.5-1% of your messages bounce due to these normal factors, and that's just fine.

However, if you are seeing a high bounce rate, it's likely because there is an issue with how contacts are being added to your list, or perhaps they need to be sent communications more often. Below are methods you can start using today to reduce your bounce rate.

  1. Use a double opt-in with your subscription form
    Using a double opt-in with your subscription forms serves two primary purposes. First, you are eliminating any invalid email addresses that contacts may have entered due to a typo or spam submissions by bots. Second, you ensure that contacts own their email account and want to hear from you.

    If you use an ActiveCampaign subscription form, the double opt-in option feature will default to "On." To ensure this is on, click "Website" on the left to navigate to the Forms page in your account. Then click "Edit" for your form. From there, click the "Options" tab. Under "Form Action," click the Gear icon next to the "Subscribes to List" action. You should get a pop-up screen where you can check to make sure that the double opt-in is enabled.

  2. Add a Captcha to form
    Adding Captcha to your subscription forms will prevent bots from creating spam contacts in your account, whether or not you have enabled the double opt-in on your form.

    To add a Captcha field to your form, click "Website" on the left to navigate to the Forms page in your account and click "Edit" for your form. On the "Fields" tab, click "Standard" and drag the Captcha field to your form.

    Note that Captcha can only be used with Inline form types.

  3. Send communications in set, regular intervals
    If you have not communicated to your list in a while, some email addresses may no longer exist. This will result in bounces, and your sender (ActiveCampaign) can be marked as a spammer. In addition, if you do not email your list regularly (or if you haven't cleaned it in a long time), you risk your subscribers "forgetting" about you and marking your email as spam.

  4. Set up Engagement Management automations
    We have a free 2-part automation recipe that you can use for engagement management. This 2-part automation will tag your contacts as "Engaged," "Disengaged," or "Inactive" based on how much time has gone by since they have interacted with your communications. These tags can be used in analytics, segmentation, list hygiene, and triggering other automations.

    Learn how to set up the Engagement Management automations in your account. 

  5. Use real-time verification services as an extra safeguard
    Services such as Briteverify can preemptively identify a bounce by pinging an email address at the time of sign-up to see if it's deliverable. This is recommended for senders who have thousands of sign-ups a day.

I have a valid contact that bounced. Why did that happen?

Usually, this happens because the recipient's inbox provider decided to block the message you sent for one reason or another. This temporary error should resolve itself, assuming the contact is valid.

However, in some rare cases, the inbox provider will make a mistake and give us a misleading bounce code saying the address is invalid when it was bounced for another reason. If this happens, we'll take the inbox provider's word and treat the account as invalid (hard bounce), even if this isn't true. If you know a specific bounced address is valid, contact our Customer Experience Team, and we can help you.

Please note that a hard bounce can only be adjusted by contacting our Customer Experience Team. Resubscribing a hard bounced contact to a list manually within your account will not successfully update the address as valid. This can only be achieved by contacting our Customer Experience Team.

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