How Bounce Rates can Help you Keep Your Sender Reputation and Mailing List Healthy

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Zakiya Fulton-Anderson
Zakiya Fulton-Anderson


As email marketers, we know that maintaining a healthy sender reputation is highly important as it pertains to email deliverability. It is a key determinant in whether emails reach the primary inbox or land elsewhere. We also know that following email deliverability best practices is a surefire way to build, recover, and maintain a healthy sender reputation. For example, we know not to send to contacts with whom we do not have a relationship, permission to email or clear expectations as to what and when you will be emailing them (remember N.O.P.E.?).

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However, when we begin to think about all the things that can negatively impact a sender’s reputation, we can easily end up in the weeds. There’s a lot of information to process! My goal with this post is to discuss the things we can control to turn around sender reputation and effectively improve your chances of reaching the coveted primary inbox.

So where do we begin? Bounce Rate.

What Is a Bounce?

When a bounce happens, it is essentially the end of the line for your email. This is perhaps one of the most frustrating aspects of email marketing! You’ve spent precious time and calories building a fantastic email campaign only to find that it could not be delivered. What gives?

A bounce is a non-delivery event, meaning there was a permanent or temporary problem with delivering to a recipient’s address. When using an ESP (email service provider) to send email on your behalf, bounces are typically processed and parsed out in-app, making it easy for you to understand what happened. If you are a HubSpot user, you can learn about bounces on the Recipients tab in the post-send details of an individual email campaign. There, you can find which emails have hard bounced or soft bounced.

A hard bounce indicates that there was a permanent error with delivery to a specific contact. For example, a contact’s email address may be invalid, unknown, or the recipient’s server has rejected mail from your domain or IP. At HubSpot, we suppress hard bounces from future sends, protecting your sender reputation and deliverability from further damage. Soft bounces, on the other hand, are temporary issues that can occur for many reasons but can ultimately be resolved. We’ll cease any attempts to deliver the original email that resulted in a soft bounce, but the contact is not marked as ineligible for future sends (more about bounce classifications here).

The key takeaway here is that a non-delivery report – or bounce – comes directly from the recipient’s server. Contrary to some beliefs, bounces are not made up by, nor are contacts blocked from sending by, ESPs.

So What Does this Have to do With Sender Reputation?

Email marketing is all about sending the right email to the right person at the right time. Sending to bounced contacts is hardly conducive to this goal. And I get it, we can never know for sure when a contact will bounce or become ineligible. However, high hard bounce rates is an indication of poor list health and a signal that it is time to clean up your contacts database. Paying close attention to hard bounce rates can also help uncover problematic contact sources, as well as explain lower than average open rates and click-through rates. If contacts hard bounce, how could they receive an email, open it, and engage with it? If contacts hard bounce, why keep them on your list?

Your relationship with contacts should be thought of as a symbiotic one: you send to those who are interested in your mail and in return, they will open and engage with it. You score reputation “points” with every engagement, and your contacts get information that adds value. Repeatedly sending to bounced contacts does not fit into this equation as every send to an ineligible or unengaged contact means your sender reputation takes a hit. Not to mention, this kind of behavior trains ISPs to place your mail directly into the spam folder, as opposed to the inbox.

The next time you review your marketing email performance, take a peek at the bounce rate! If your hard bounce rate is at 1% or higher, it is a signal that your emails are not reaching their intended audience and your sender reputation may be suffering. What can you do now to recover from higher than average bounce rates? Consider these three easy steps for getting your bounce rate under control:

  • Send to smaller segments of your contact lists to drive engagement.
  • Tiered sends: send to your most engaged contacts first. If they open and engage with your mail, you know for sure it reached the inbox. Slowly layer in less engaged contacts.
  • Implement a contacts database cleanup strategy, such as a sunset policy, to regularly remove ineligible and unengaged contacts.

Remember, bounce rates are simply an indication that your contact lists and sender reputation could use some attention. The recommendations above are steps in the right direction to help you improve email deliverability down the line!

Did you know: Verified opt-in is now required for all contacts to be sent email from the HubSpot platform. Check out HubSpot’s Acceptable Use Policy for more information.

Want to connect with others on HubSpot tips, tricks, and updates? Head over to the HubSpot Community to join a conversation or start one of your own.

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