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Making Sense of Email Bounce Rates

JAMES SMART - FEB 22, 2017

Bounced email addresses can be one of the most frustrating aspects of email marketing. A bounce means your reader didn’t get the information they wanted to get and you wanted them to see. But a bounce is something technical that only delivery pros can deal with, right? Nope. In fact, there are many things you can do to help your emails make it to your readers’ inboxes.

In this post, we’ll go over the differences between hard and soft bounces, why they occur, and how to prevent and resolve issues with high bounce rates.

What is a bounce?

An email bounces when it can’t be delivered to a receiving email address. The reasons can be permanent or transient, solvable or irreparable, so when a bounce occurs, a return to sender message is sent back from the recipient’s mail server to help diagnose the issue. Bounces are usually categorized as either hard or soft, depending on how series the problem is.

What’s the difference between a hard and soft bounce?

Hard bounces are permanent delivery failures. This could be as a result of an invalid, erroneous address, an outdated domain, or an address which has fallen out of use. At Campaign Monitor, if an email is marked as a hard bounce it’s automatically suppressed and won’t be sent to again.

Soft bounces are temporary delivery failures and can occur for a variety of reasons. There may be a temporary issue with the receiving server, the recipient’s mailbox may be full or the receiving server may have identified an email as too large, to name just a few. There are many reasons that soft bounces occur, though by carefully maintaining your list and ensuring your data is sourced with opt-in permission, you can mitigate the potential for these kinds of bounces.

In most cases, an address will soft bounce five times before being automatically converted by Campaign Monitor into a hard bounce.

If you’re seeing bounce rates above the 2% industry standard, continuing to send to those addresses without action and investigation on your part will damage your sending reputation with receiving ISPs and will degrade the deliverability of your future sends.

What is a high email bounce rate?

It’s important to understand that a small number of bounces are to be expected over the lifetime of an email subscriber list. Addresses are changed or abandoned by their owners, people change roles or jobs, and temporary delivery issues can result in a small number of bounces too. The benchmark for bounces is less than 2%. Anything above a 2% bounce rate for your email campaign is worthy of your attention. If you’re seeing bounce rates over 5%, or even as high as 10% or greater, this suggests a significant problem that you will want to resolve.

Now that we’ve covered why email addresses bounce, you’re probably asking yourself if you can do anything to prevent high bounce rates? Although there are some aspects of email delivery that are out of your control, there are still plenty of things you can do to make sure you have a low bounce rate.

Use permission-based, opt-in data

It all starts with your list. Lists that are not created with opt-in permission of each individual recipient are more likely to see issues with high bounces and invalid addresses. Ensure you are in compliance with our policies, that your lists are built with permission and that your sign up forms include an opt-in checkbox.

Non-compliant sources such as scraped, purchased or third party email addresses are strictly prohibited from use at Campaign Monitor and will always see issues with high bounces, low engagement, and deliverability.

The key to the success in email marketing is the strength and compliance of the list – use only opt-in, permission-based lists that comply with our policies and best practices and you will already be on your way to engaged, active lists with low bounce rates.

Be smart with incentivized signups and competitions

Common sources of email addresses that see high bounces are competition forms, WIFI sign-up pages (where you get free WIFI for signing up) or other incentivized sign-up forms.

Sometimes, people are tempted by a competition prize or want to sign up to use WIFI though they do not wish to be added to a mailing list. These people use fake addresses or abandoned mailboxes in order to take advantage of the offer without receiving future emails.

Step one, as always, is to be compliant with our policies and ensure that you have an opt-in checkbox on your sign up form so that only people who check the box and want your emails are added to your list. Be clear with your subscribers about what they will be receiving and let them know they can unsubscribe at any time.

Show the value of your newsletter at sign up and make sure that your content is valuable and relevant. Bad newsletters with good incentives attract bad addresses that aren’t likely to engage with your emails. Give people a reason to sign up beyond any incentives for becoming a new subscriber and give them absolute clarity about what they are signing up for.

Use confirmed opt-in

Confirmed opt-in can help assure data quality across all of your subscribe forms. By ensuring that people must activate their subscription with a confirmation email, any erroneous or inactive addresses simply won’t make it onto your active subscriber list. This can greatly reduce potential bounces, and lists using confirmed opt-in tend to be more engaged and active too.

Don’t use a free domain send-from address

Using a free domain email address such as Gmail or Hotmail can mean that your emails will fail a DMARC check by receiving domains operating a DMARC policy. Your emails will automatically bounce at Gmail and Yahoo and are likely to be bounced or be routed to junk by many receiving domains.

Be sure to use a send-from address at your business domain and authenticate it too. This will help ensure your emails are not caught in spam filters unnecessarily. Not only will you improve your bounce rates but your general email deliverability will be improved.

Send consistently and frequently

Regular, consistent contact with your subscribers is an integral part of a successful email marketing program. Lists can go stale in as little as 6 months, and lists that have remained dormant over a longer period of time can see issues with engagement and spam complaints, as well as with bounces.

Send your recipients a welcome email to engage them from the start, and send them regular, relevant communications.

People often change their email addresses or leave previous ones abandoned which are subsequently likely to bounce. By contacting them regularly, you can be sure any bounces happen in low numbers over time, rather than seeing a large number of bounces at once from a list that is only contacted sporadically.

There is no one size fits all solution to email sending frequency, though if you only email your subscribers a couple of times a year, you should probably connect more regularly with your subscribers so they expect to hear from you on a regular basis and engage when they do.

Use a preference center

Be sure to include a preference center link in your emails so that people can update their email address and encourage them to do so. Not only can this have a positive effect on preventing future bounces, but giving people control over the emails they receive is great for engagement and for cultivating trust too.

Use a list verification service

If your list has been dormant for a period of time, or if you have been sending via a system with less than stellar bounce management systems, you may want to use a third party list verification service to identify and remove undeliverable addresses ahead of sending.

You can use our App Store to integrate with services such as BriteVerify or Kickbox and verify your list.

Removing the undeliverable addresses is a no brainer, though you may also see some services classify some addresses as risky, or unknown. In those cases, removing them entirely may not be the right step, though we would highly recommend staggering sends to those kinds of addresses.

Add a small number of those risky or unknown addresses to your list to begin with, monitor the results, and then add some more if all goes well. If you see high bounce rates from these addresses, you may want to rethink using them at all.

Preventing a huge spike in bounce rates by proceeding carefully with riskier data is essential for good email deliverability. Inbox providers and spam filters pay close attention to bounce rates and attempts to deliver mail to invalid addresses. If your bounce rates are sufficiently high, they may take steps to reject or block your emails entirely, and you could see bounces at legitimate inboxes too.

By verifying your list and adding any risky or unknown data steadily, you will prevent undue damage to your sending reputation and help the delivery of your emails with all inbox providers.

Be vigilant and monitor your results

As with engagement and other deliverability issues, the longer you leave bounce issues to fester, the greater the damage to your sending reputation. Monitor the results of your campaigns and journeys closely. If you see a spike in bounce rates, take a look at the bounce activity report. Are you seeing an influx of hard bounces, or have you see a huge upswing in soft bounces, perhaps at a particular domain?

Take action to improve your sign-up form, double check your data sources and the age of your lists. Ensure your authentication is in place and that your send-from address is from the same domain. If you’re still at a loss over why you are seeing high bounce rates, reach out to our support team, who will be able to help diagnose and resolve any issues.

Authenticate your emails

Email authentication is now one of the most important factors in a strong email marketing strategy. Failing to authenticate your sending domain means that receiving servers are likely to bounce or junk your emails as they cannot determine the legitimacy of your sends.

By authenticating your sending domain, you are proving the legitimacy and authenticity of your emails to receiving ISPs and this alone can have a profound effect on reducing soft bounces and improving the deliverability of your email campaigns in general.

Ramp up

In the event that you have a large email list that has not been sent to for some time, you’ll want to ramp up your sends carefully and monitor the results of your smaller campaigns ahead of sending to the full list.

Sending to the entirety of an older list and seeing a large number of bounces can be a disaster for the deliverability of your future emails. By sending to a smaller segment of your list first, you can monitor the performance and take steps to improve those results. By ramping up to send to your full list steadily, you can better control the impact of your campaigns, course correct if necessary, and preserve your sending reputation.

Wrap up

The key to understanding email bounce rates is to acknowledge that a small number of bounces are always to be expected, but preventing a large amount of bounces is often in your control. High bounce rates are usually an indicator of issues with the age, permissions or previous maintenance of your email list. By following the above steps and taking ownership of how your list is created and maintained, you can prevent high bounce rates and see further success with your email campaigns.

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