Bounced Emails: How to Fix and Improve

The Warmup Inbox Team
The Warmup Inbox Team

What Is an Email Bounce?

An email bounce occurs when a message is unable to be delivered to the intended recipient. When an email bounces, the sender receives an automated message from an email server that informs the sender that the message didn’t get through to the intended destination. An email bounce indicates that something has gone wrong in the sending process, and it could be a result of the sender or the recipient.

You’ll receive a Non-Delivery Report (NDR) either from your sender or the recipient’s sender detailing what caused the delivery failure.

When you send out an email, the message is given to your SMTP server for delivery. It’s like dropping off a package at the post office. Your SMTP server will check the DNS to locate the recipient’s server, and once they know where to transfer the message, their Mail Transfer Agent (MTA) takes the message over to the recipient’s server. In this case, the MTA is the postman.

At this point, the recipient’s server gets the message, and one of two things happens. One: they push the message through to the recipient’s inbox, and the recipient gets to read your incredible content. Or two: the recipient’s server decides that they don’t want to accept your message, so they send it back to you.

Of course, we’re all aiming for option one. Thankfully, emails are generally bounced for a specific reason, and most of the time, it’s an easy fix.

What Causes an Email to Bounce Back?

There are a variety of reasons that an email could get bounced, but bounced emails are typically caused by one of three scenarios:

  1. Lack of Memory on the Email Server or Inbox – If the recipient’s inbox doesn’t have enough memory to store another email, the email will bounce back to you. This scenario is rare these days, but it does happen occasionally.
  2. Unreachable Destination – If you send a message to an email address that doesn’t exist, the email will bounce. If a mail server can’t locate the target destination of a recipient’s inbox, it will bounce the message back to you and let you know that the address doesn’t exist. This doesn’t necessarily mean that the address never existed, but it could indicate a deactivated email or a typo in the address.
  3. Failed Validation – If you send a message to a server with advanced security protocols in place, the message may bounce back to you. Authenticating your domain through SPF, DKIM, and DMARC can help with this. Be aware that multiple failed validation bounces can also indicate that you’ve been placed on a blocklist.

What Are the Differences Between a Soft Bounce and a Hard Bounce?

Soft Bounce

  • A soft email bounce occurs when a server temporarily rejects an email. With a soft bounce, you should have no problem attempting to send an email to the same address in the future.
  • Soft bounces can occur when a person’s mailbox is too full, if the email you’re sending is too large because it’s stuffed with large images or attachments, the server is down, or if the recipient sets up an autoreply when they’re away from their inbox.
  • Soft bounces aren’t the end of the world and aren’t something you can control, but they do have a small impact on your sender reputation and a more significant impact on your deliverability rate.

Hard Bounce

  • A hard email bounce occurs when a server is unable to deliver a message to an email address, and there’s no way to deliver the message at any point in the future.
  • Hard bounces can occur when someone gives you a fake email address, an address is typed in incorrectly, the recipient has blocked your email address, a spam filter was unable to authenticate the message, or you’ve been put on a blocklist.
  • Hard bounces are more detrimental to your sender reputation, but you can avoid hard bounces by verifying email addresses before sending correspondence and continuously practicing good sender habits.

How to Reduce Your Bounce Rate

  • Keep Your Email List Clean and Up to Date – Consistently maintaining a clean email list will help you avoid any unnecessary bounces. Additionally, don’t buy email lists from people who say they have matches for your target audience. These lists are often filled with inactive emails and spam traps and can get you into more trouble. It’s better to take the time to build your subscriber base organically.
  • Verify Emails Before You Send – When you conduct an email collection drive, it can be tempting to start sending emails right away. But people make typos all the time, and that can lead to avoidable bounces. Verifying emails before you add them to your mailing list saves you from sending emails that will inevitably get bounced. At the same time, you can use a verification service to frequently verify that the emails on your list are in good standing and identify any emails that would result in a soft bounce.
  • Authenticate Your Domain – Taking advantage of SPF, DKIM, and DMARC in your DNS settings helps validate that your messages are legitimately coming from you. This helps ISPs and spam filters recognize your domain and pass your message through.
  • Warm Up Your Inbox – Before you begin a mass email campaign, prepare your domain to be ready to send a high volume of emails. The warmup process can take anywhere from 4-6 weeks and will significantly lower your bounce rate. And the good news is that we can help you with that.
  • Use Confirmed or Double Opt-in Measures – Giving your subscribers the chance to agree to receive content from you makes it more likely that their ISPs will allow your message to go through to their inbox. Additionally, it gives you the opportunity to let the customer check that their information was entered correctly before you begin sending them messages.
  • Allow Your Recipients to Unsubscribe –While your goal is obviously not to lose customers, respecting their ability to opt-out benefits you in the long run. If customers are able to unsubscribe, they can hit that button instead of reporting your message as junk or spam. Too many spam reports lead to a damaged sender reputation, so it’s better to give subscribers an easy way out that doesn’t affect your ability to continue reaching the customers who want to see your content. It’s also crucial to honor unsubscribe requests quickly, so you don’t have any bounces from unsubscribed addresses.
  • Avoid “Spammy” Content – Certain words you use in your emails can raise red flags for ISPs. Proofread your emails before you send them, and maybe take the time to run them through a spam checker.

How to Fix and Improve Your Bounce Rate

Your bounce rate is calculated by dividing the number of bounced emails by the total number of emails you sent, then multiplying the number by 100 to generate a percentage. A good bounce rate is anything under 2%, and 5% or more is considered critical. To put it simply, if you have a 2% bounce rate, for every 100 emails you send, only two bounce back.

If your bounce rate is in the danger zone, there’s no need to panic. Depending on how high your bounce rate is, you may want to check whether you’ve been placed on a blocklist and get your domain removed as quickly as possible.

When you’re clear of all blocklists, you can begin working to repair your reputation and lowering your bounce rate by implementing the practices listed in the section above. And if you need help warming your inbox back up, we’ve got your back.

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