Why Do Emails Bounce | How To Lower Email Bounce Rate?


A beautifully crafted email can do wonders for a business trying to get new leads or clients.

There have been countless success stories of companies or businesses that made record sales following a successful cold-email campaign.

However, with the growing popularity of cold email campaigns, scammers and fraudsters are moving into the cold emailing territory. You must have heard of scammers and frauds targeting older people. They target the unaware and vulnerable section of society and rob them of their hard-earned money.

To crack down on this injustice, more and more ISPs (internet service providers) are using considerable resources to code spam traps into their email services.

A spam trap is a predetermined set of conditions that determine whether an email is spam. A spam trap can put you on an Internet Service Provider’s (ISP’s) blocklist.

An Email Service Provider (ESP) might also decide to put your email address in the block list. 

As well-intentioned as spam traps might be, they rob hard-working businesses and companies of a valuable resource for acquiring new business.

Ending up on an ISP or ESP’s blocklist will mean that your email is not going through your prospect’s inbox. And that might cause an email to bounce.

In this article, you will learn more about how an email bounces and how to avoid a high email bounce rate for your email campaign. 

Email bounce: What Is It?

Imagine this scenario – you spend considerable money crafting an informative, funny, and thoughtful email. The email you will use for your cold-email campaign has been acquired through many resources. In the end, when you deploy your email campaign, you realize most of your emails have not been delivered or have bounced back. When this happens, it is called an email bounce. When an email bounce happens, you get an error message that the email you have sent isn’t delivered. Your email server or the destination (recipients) mail server sends this Non-Delivery Report (NDR). An email bounce message also informs you what caused the delivery failure of your email.

What Causes an Email to Bounce Back?

There are many reasons for an email to bounce back. Before we can figure out how to resolve the issue of high bounce rates, we need to look into what causes an email not to reach its senders. There are five primary reasons for an email to bounce back. 

  • Full inboxes
  • Unresponsive servers
  • Emails sent to false email addresses
  • Emails sent to email addresses that no longer exist 
  • Your email address is on the ISP block list. 

These unsent emails fall under three categories of email bounces. 

  1. Soft bounce emails
  2. Hard bounce emails
  3. Blocklisted emails

Let us see what these three types of email bounces entail and how to troubleshoot them. 

  1. Soft bounce emails

If the email receiver server rejects your email temporarily, you have a case of soft bounce emails. Soft bounce emails are usually temporary, and you can re-send the email after a week or two has passed. Here are some reasons for a soft bounce:

  • A full inbox: An email server will give users limited email space. Once a user has used that space, there will be no space to accept emails. In this case, your email will bounce back until there’s free space.
  • Email size: Multimedia-heavy emails may bounce back because of filters put in place by the ISPs or the users themselves. The attachment size limitations depend on the ISP 
  • Autoreply: This feature is used when the email recipients are not reachable for extended periods. An auto-reply will make an email bounce back.
  • Unresponsive server: Sometimes, email servers can go into overload and crash. Unresponsive servers can also be a result of maintenance. 
  1. Hard bounce emails 

A hard bounce means that your email won’t go through at all. There are several reasons for it.

  • Misspelled email addresses: This can cause an email to a hard bounce. Make sure to avoid spelling mistakes while typing out email addresses. 
  • Disposable emails: With the emergence of services like temporary emails or disposable emails, it’s becoming easier than ever to have your emails not delivered to any address. 
  • Fake email addresses: Sometimes, people give out fake ones when asked for them. The best way to avoid this is by verifying through double opt-ins.
  • Blocked: If the recipient blocks your email address, then there is no way you can get your email to them. 

The best way to troubleshoot this issue is to delete these hard-bounced email addresses. Too many hard bounces can get your email address blocklisted. 

Learn what is soft email bounce

  1. Blocklisted emails

Spam is becoming more and more prevalent each day. Therefore, ESPs (email service providers) create email blocklists to filter out harmful email content like malware and spam. Make sure your email address doesn’t end up in the ESPs blocklist. Let us look into how an email gets into an ESPs blocklist in the first place. 

  • A surge in email volume: If you scale up your email send list too suddenly, it can point towards buying an email list. This mirrors certain spam practices and can land you in the ESP blocklist. 
  • High bounce rates: You will get high bounce rates if you keep using the same old email send list without clearing the blocklisted emails. 
  • Spam complaints: If your email address receives too many spam complaints, your email might end up in the ESP blocklist. 

Being on a blocklist can hamper your campaign adversely. There is a high chance that your email doesn’t reach the inbox of anyone in your campaign email list. But fret not; here are a few email hygiene practices to avoid ending up on anyone’s blocklist. 

  1. Don’t use spammy language while sending your email. Think of ‘LIMITED PERIOD OFFER’ or ‘BUY NOW OR REGRET FOREVER’ in caps followed by overuse of emojis and exclamation marks may trigger spam filters. 
  1. Remove dead-ended emails from your campaign’s email list. 
  1. Change your IP if you have been blocklisted. Changing providers can keep you off the ESP’s blocklists. 
  1. Never ever buy an email list. It may seem like an easy and shortcut way to get a ready-made campaign email list, but you can’t judge the quality of the email list, and it is the fastest way to get your IP address onto ESP’s blocklists. 

If you find yourself in a sticky situation where you are on a blocklist, and you need to get off of it because, say, you can’t change ISP, then there are some ways to get off the blocklists.

  • First off, give it time. Most blocklists will remove a blocked email after a certain amount of time. 
  • Most blocklists can be accessed publicly. Contact the blocklist website holder if you find your email address on one of these lists. A well-formatted email can do very well to persuade the blocklist provider to remove your email from their blocklist. 

Email bounce is more common because Internet Service Providers (ISPs) and individuals are making spam filters more diverse. Therefore, if your email contains a sentence that is recognized by the spam filter, it will not reach your leads. Your email bounce rate should stay below 3%. An email bounce rate of anything above 2 percent should be investigated. 

Which Criteria Are Increasing My Email Bounce Rate?

There are many ways to ensure that your email ends up in your lead’s primary folder instead of getting bounced back or ending up in the spam folder. Here are a few common criteria that might trigger a spam filter:

  • Emails with no words in the body but just an image. 
  • Having several duplicate links on the same email page.
  • A sender email address that has been problematic in the past. 
  • Words that might suggest that the email is sensationalizing a service or product. 
  • Phrases that are common in actual spam emails like “Hurry now…” or “limited time period offer….” or “offer of a lifetime!”

The abovementioned criteria are just broad strokes of what a spam filter might contain. Something as simple as a ‘Hi,…” at the beginning of a sentence might trigger a spam filter. 

How to Lower My Email Bounce Rate?

Your email campaign’s success depends on its reach. With a high email bounce rate, you are decreasing your reach. Here are a few tips you can follow to make sure your email grabs the right eyeballs. 

  • Verify your email list: Verify the authenticity of the emails on your list by using single email verifiers or bulk email verifiers
  • Consent-based emails: Send emails to only those who have consented to receive your emails. 
  • Send emails often: Sending emails to your campaign email list regularly will rule out the possibility of your IP ending up on a block list. Send emails regularly but at random intervals to decrease your chances of ending up on a spam list. 
  • Segment your email list: Segment your email list according to engagement. Send emails regularly to the segment that has the highest engagement. This shows the ESPs that you have highly engaging content that provides value. 
  • Give your recipients a choice on what type of emails they want to receive and how often they want to receive them. 
  • You can also check your sender’s reputation score. You are less likely to end up on the primary inbox page of your leads if you have a low reputation score. You can check your sender score from websites like Talos Intelligence by Cisco or Sender Score by ReturnPath. 

A lot of the solutions discussed above can be a good springboard for your effort to lower your email bounce rate. However, this is not an exhaustive list. Employing an ABP (Account-Based Prospecting) style email campaign will address most of your issues about not having a high email bounce rate. ABP-style email campaigns also, on average, bring in more responses than a normal cold-email campaign. But do remember that when using ABP, if either prospect’s email bounces due to “email blocked,” the entire list of emails might probably bounce. Consider this when creating a strategy for sending emails.

SmartReach.io specializes in cold email campaigns. It has special features like spam test reports, email validations, campaign soft start etc that directly or indirectly assist in lowering your email bounce. Its advanced personalization features also prevent the triggering of ESP’s spam filters that might get you on their blocklists.

There is a science and art to understanding the intricacies of a mass-deployed email campaign. With so many moving parts in action, it can be hard to keep track of certain things. SmartReach ensures that your emails reach the primary inboxes of the highest-quality leads or prospects. Our specialty software also makes it easy to replicate the human tone that is necessary to connect to a lead on a personal level. This level of care and personalization allows the prospect to convert into a sale. 

To sum it up

Any email campaign bounce rate over 3% should be investigated.

A successful campaign is possible if you avoid the common traps of spam filters and avoid spammy behavior.

Most organizations nowadays use personalized systems to craft successful email campaigns. It is known as ABP (Account Based Prospecting)-an emailing system. This results in personalized emails to individuals of a particular company that is part of your ICP; as a result, a higher email response rate!

Ultimately, you should try your best to keep your email bounce rate low. We acknowledge that complete elimination of the bounce rate is not possible, but the methods mentioned above should be a good starting point. Remember these few key pointers:

  • Rectify server and IP issues as soon as they happen. 
  • Organically grow your leads list instead of buying premade lists. 
  • Honor opt-out requests from your emails. 
  • Clean up your email list. Remove emails that have hard-bounced in the past. 
  • Send a high-quality email that doesn’t have spammy and sensationalizing language.

Following these broad guidelines will allow you to send high-quality emails for your campaign. These guidelines will also ensure that your bounce rate stays at a minimum. 

You deserve to give your business a fighting chance in this day and age. Avoiding pitfalls like high email bounce rates ensures your business reaches the people needing it the most. 

Frequently Asked Questions (FAQs)

1. Can I buy email lists and use them on my campaigns?

The short answer is no. You should never buy an email list and use them on your campaigns. There are several reasons why: 

  • Buying off a list can surge your send rate. This will put you on a block list immediately
  • It violates CAN-SPAM guidelines. 
  • Most ESPs can tell the difference between organically grown and bought-off lists.  

Our suggestion to you would be to grow your already existing email list by using Linkedin prospecting tools like ProspectDaddy which give you a business email. 

2. How do I prevent violating CAN-SPAM guidelines?

The CAN-SPAM guidelines might sound complicated initially, but you only have to follow a few basic guidelines:

  • Avoid misleading header information. 
  • Accurately summarize email content in the subject lines.
  • Tell your recipient that the email is an advertisement if the email is indeed an advertisement. 
  • Give recipients options to opt out of future emails. 

3. Will my bounce-back rates stay low if I hire a company to send the emails on my behalf?

You can hire companies that specialize in managing cold email outreach campaigns. However, hiring a trustworthy company is important. SmartReach.io can help you customize cold email outreach campaigns with low bounce-back rates. We do this by conducting spam tests on your emails and validating a prospect’s email through its email verification software. Furthermore, we will also help build up your email’s sender’s reputation by soft-starting the email’s initial send rate. 

4. How do third-party websites evaluate my sender’s reputation?

When you first create your email, you have a neutral sender’s reputation. But based on the amount of engagement your emails have, your reputation score is developed. Your sender’s reputation is determined by how your leads engage with your email. To keep a favorable sender’s reputation score, only send emails to verified leads, and start your campaign by sending only a few emails at the beginning. 

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