How to reduce email bounce rate is one of the most common challenges digital marketers face today. The ROI of your email marketing campaign can go down seriously if you aren’t within the acceptable email bounce rate range.
Before discussing the ways to control email bounce rates, let’s quickly understand the meaning and types of email bounces.
What are bounced emails?
Bounced emails are those email which could not be successfully delivered to the recipient email address and were returned to the sender address with return message. That’s because your subscriber’s email server rejected the email you sent to them.
How email bounce rates affect your marketing campaign?
Paying attention to the rate of bounced emails is important for a variety of reasons. Here’s some of the reasons you need to keep a close watch on bounced emails and ensure they remain absolutely within safe limits:
- They can reduce your overall email delivery rate
- They lower your sender reputation in the eyes of ISPs
- They hurt your email marketing ROI
- They can cause you to be labelled a Spammer
- Your Email Service Provider can penalize you or decline carrying your mail
- If left unattended for a long time, email bounce can cause serious problems with the law, like with the US CAN-SPAM Act, among others
What are the types of Email Bounces?
There are two kinds of email bounces: 
- Hard Bounce
- Soft Bounce
What is Hard Bounce?
Emails that bounce because those email addresses either no longer exist or are incorrect are called Hard Bounces. No matter how often your ESP tries, the email will not be delivered since the email address does not exist in the first place. Think of them as permanently unreachable addresses. If, however, your campaign shows too many hard bounces, probably your emails are hitting the Spam Filter of recipient.
Some of the reasons for Hard Bounce include recipient server has blocked incoming email, the address is incorrect, the domain is incorrect or the email address no longer exists.
What is Soft Bounce?
Emails bounced because the recipient’s server was down or her mailbox is full are called Soft Bounces. Your ESP may try delivering your emails, but will most likely abandon efforts after approximately 5 failed attempts.
Soft Bounces aren’t nearly as bad as hard bounces, but they can certainly reduce your delivery rate, to say the least.
Soft Bounces occur when the recipient’s email server is down or offline, the email size is larger than what the email server permits or the mailbox has exceeded its capacity.
How can you reduce email bounce rates?
Now with the basic understanding out of way, let’s focus on the most proven methods to make sure your email bounce rate is as low as possible.
Below are the series of steps you may take to prevent emails from bouncing and improve the deliverability rate of the emails you send out.
1. Use double opt-ins. Always
The first step starts even before you send out your email. It focuses on how you append email addresses to your mailing list.
Anyone who keys in her email address to join your mailing list must be first sent an email. The recipient must agree (typically by clicking on a link in the email) to keep receiving your emails.
This action serves two purposes:
- Firstly, the email tests whether the address was typed correctly.
- Secondly, it ensures the recipient of the email is the same person who keyed in the address.
2. Start only with a clean email list
Most likely some API or tool already cleaned your database. Besides, you already have a double-opt in so ideally you shouldn’t worry, right?
Well, not exactly. May be someone joined your database before you started double-opt in. May be some email addresses are no longer valid today.
Estimates vary, but in B2B cases, it is estimated around 23% addresses die every year. So it’s always a great idea to kick-start your email marketing campaign with a cleaned list. Email List Verification companies provide reliable and accurate services at favorable price bands.
3. Prime your IP to success by starting small and accurate
This escapes the notice of most marketers.
Your IP must establish a reputation of being ‘good’ and ‘reliable’ so that ISP filters don’t doubt your authenticity. So how do you build that kind of reputation?
It’s a smart idea to start your email campaign by sending out emails in smaller batches to addresses that are absolutely in the loop and fully engaged. Basically, start by sending out emails to a small number of people who you know will open your emails and not mark them Spam.
The ISP filters notice your emails didn’t bounce, were not marked Spam, and got a high open rate. Now it starts trusting you.
Do this for increasingly bigger sizes and ISP filters will start trusting you fully.
4. Use email authentication
Service providers like Google, Microsoft and AOL, amongst others, use a specific form of authentication when checking incoming email. If the incoming email fails the authentication test, it will most likely land in the Spam Folder.
To avoid this happening to your emails, it’s best to get your emails authenticated.
At least two types of authentication are recommended: SPF and DKIM.
SPF (Sender Policy Framework) is basically a DNS text entry. It shows servers(IPs) that are considered safe to send emails for a specific domain. SPF helps a domain owner insert a file or record. This entry is cross-verified by the recipient’s server. This mechanism allows receiving email servers to verify the incoming mail from a domain comes from a host authorised by the domain’s administrators.
DKIM (DomainKeys Identified Mail), on the other hand, is a mechanism that ensures the message has not been altered from the time it left the sender’s servers. DKIM implants a DNS entry or information inside the email. This embedded or implanted entry inside the email is extremely difficult to counterfeit. This will be used by the recipient’s server to verify that all’s well with the message contents.
Put together, SPF and DKIM not only bring a strong authentication process, they also make your email marketing campaign more professional and authentic.
Finally, there is DMARC (Domain-based Message Authentication, Reporting and Conformance). It fits inside the recipient’s email server authentication process. If the incoming mail fails the SPF and DKIM tests, the DMARC reports to the domain-owner registered with the DMARC records and conveys that the authentication tests have failed.
5. Keep tracking if you have fallen out of favor
This is completely a back-end activity.
From time to time, you will need to keep checking whether you or your email provider have been blacklisted by DNSBL.
There are spam databases and blacklists maintained by various agencies (for instance Spamhaus). They diligently track spammers and add servers (IPs) or domains of suspected spammers.
There is one thing you need to understand here: these databases will not get in touch with you in advance when they mark you a spammer. That means it will be your responsibility to keep of track whether you’ve been blacklisted, whatever the reason. If blocked, you’ll begin receiving bounces, provided your recipient server is using that specific DNSBL.
6. Your email shouldn’t look like Spam
Email servers are always sniffing around for signs of Spamming. That’s because they want the recipients to have the best of experience and protect them from as many Spammers as possible.
A choice of a single phrase can oftentimes make the recipient’s server classify your email as Spam. For instance, many experts advise marketers to stay clear of trigger words – words that are likely to raise eyebrows and question your email’s authenticity.
In our search on how to write great email subject lines, we often forget that words like, “Online degree” or “No investment” are dangerous when used in Subject Lines. There are many more words you’ll want to stay clear of; perhaps you’d like to read this HubSpot post which has a list of spam-trigger words.
While Spammers try to circumvent the recipients’ mail servers with shrewd tactics, the servers themselves are constantly learning. That means what was considered safe yesterday may be a no-no today.
To the marketer it means being constantly alert, seeking out what servers consider unhealthy and making sure their own emails are free from any inadvertent slips.
If you follow best practices of email marketing and the tips mentioned above, ideally you don’t have anything to worry about. However, it’s always better to be alert.
What all things do you do to prevent Email Bounces?
