Why Are My Emails Bouncing?

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Discover the common reasons behind email bounces and learn how to fix them for better deliverability.

by Ahona Rudra

Reading Time: 6 min
Why Are My Emails Bouncing?
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This blog digs deep into finding the answer to one of the common questions- why are my emails bouncing? Emails bounce back for multiple reasons- the email address doesn’t exist, the recipient’s inbox is full, server outages, poor sender reputation, and restrictive DMARC policy in the record for your sending domain.

Some reasons are temporary, while others could be permanent. So let’s see what you can do to fix them!

Key Takeaways

  1. Emails bounce for various reasons, including full inboxes, invalid addresses, and spam filters.
  2. Soft bounces occur due to temporary issues like a full inbox or large message size, while hard bounces indicate permanent issues with the email address.
  3. Implementing a DMARC policy can help prevent unauthorized senders from impersonating your domain, reducing bounce rates.
  4. Maintaining a good sender reputation is crucial for ensuring that emails do not get blocked or sent to spam.
  5. Taking steps to authenticate your domain and avoid spam-triggering words can significantly improve email deliverability.

What is Email Bounce Back?

Email bounce happens when emails you send fail to reach your recipient’s mailbox due to specific issues. This impacts your email account or domain’s deliverability rate, which consequently affects your marketing, PR, link-building, and sales campaigns. 

When an email bounces, you receive a Non-Delivery Report or NDR, informing you about the failure.

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Types of Email Bounce Back?

To find the answer to ‘why are my emails bouncing,’ you need to know the type of bounce category your emails fall under. There are 3 major types of email bounce backs.

1. Soft Bounce Emails

This means an email has bounced back because the recipient’s inbox is full, the server was down, or the message was too heavy for their inbox’s capacity. In this case, the email address is valid. 

2. Hard Bounce Emails

A hard bounce occurs when the email address is invalid or doesn’t exist. It’s a permanent reason, and hence, you should remove the email address from your mailing list.

3. Blocklisted Emails

84.82% of all emails sent and received daily worldwide are spam. That’s why ESPs filter spammy and exploitative content to protect users against spam attacks. Your emails get blocklisted due to spam complaints, high bounce rates, an increase in the email volume, or the inclusion of spammy words in the subject line like ‘OFFER,’ ‘FREE,’ ‘XXX,’ ‘SCORE WITH BABES,’ ‘EARN PER WEEK,’ etc. 

Top 10 Reasons Why Your Emails Bounce?

Now that you know the types of email bounces, let’s dig into understanding the possible reasons to get the answer to ‘why are my emails bouncing?’.

1. Mailbox Full

There’s a storage capacity for every email account, including documents and photos. Recipients don’t receive emails if this exceeds.

2. Message Too Large

When the content in the message or attachment is too large and exceeds the limit of the receiving server, the email bounces back. Emails over 10MG are generally considered too large by most ESPs. 

3. DMARC Policy

When you set your DMARC policy to reject, all emails sent from your domain that fail SPF and/or DKIM checks bounce back. This prevents unauthorized senders from tricking recipients into sharing sensitive information.

If you also observe bouncebacks of legitimate emails, try resetting your DMARC policy to quarantine or none. 

4. Vacation/ Auto Reply

If someone is off from work or can’t check their emails, they can set an auto-reply. This type of bounce back means that your messages were delivered to their inbox, and they can reply once they are back. 

If emails sent to a specific recipient bounce back with an auto-reply for months, you may want to consider removing them from the mailing list to protect your domain’s email deliverability rate.

Blocklisted

In this case, the entry of your emails is blocked by the recipient’s server due to one of the following reasons-

  • Your email address is blocklisted.
  • One of the IP addresses is temporarily blocked.
  • Your email-sending domain is blocked.
  • The receiving server is configured to accept only allow-listed senders.

6. Known Spammer

The recipient’s server marks your email as spam based on an email history or your domain reputation that indicates the exchange of phishing and spamming conversations. Here are the common reasons-

  • One of the IP addresses is temporarily blocked.
  • Your email-sending domain is blocked.
  • Reply-to address or brand name as a bad reputation. 
  • The email sent you over time to the mail server has been recognized as spam.

7.Undeliverable Email

If your NDR comes with an ‘Undeliverable’ update, then this indicates the recipient’s server is temporarily unavailable, is overloaded, or couldn’t be found. A server that can’t be found is generally crashed or is under maintenance. 

You can try resending your message after a few days. However, if you come across the same message,, the answer to ‘why are my emails bouncing’ is that the email account crashed.

8. Invalid Email Address

The email server fails to deliver the message because you mistyped the email address. You will receive NDR with the “Email address does not exist” message.

9. The Recipient Has Blocked the Email

,The recipient specifically blocked your email address and they don’t want to receive messages from you. You’ll be able to send emails only when they unblock you as an email sender.

10. Malicious Attachment Detected

The recipient’s server will block your email if it spots a malicious attachment in the message. This can be a possible virus or bug that can steal or obsolete information from the receiver’s computer. A larger attachment can also cause this issue.

How to Fix Email Bounces?

If you’ve observed an abnormal bounce rate in your email sequence, you need to take action to prevent your domain from getting permanently blocked. Here are 6 ways you can try to fix the issue.

1. Use Double Opt-In

As per the double opt-in method, new users registering with your email list must verify their accounts. This authenticates their sender reputation and helps you decrease the bounce-back rate. 

2. Authenticate Your Domain

Email authentication helps improve email deliverability by ensuring only permitted and trusted entities send emails from your domain. Start this by generating free SPF, DKIM, and DMARC records using our DMARC record generator.

3. Avoid Spam-Triggering Words

Don’t add any spam-triggering words in the subject line and message content. Words like ‘FREE,’ ‘OFF,’ ‘GET PAID,’ ‘MILLION DOLLARS,’ etc., are assumed as spammy by email service providers. Your emails can get rejected for repetitive usage of these words. It’s also suggested to avoid too many characters in caps or bold. 

Email service providers suspect emails with too many links as phishing attempts and thus block their passage to recipients’ mailboxes. Instead, you may send a file with all the links to avoid bounce-backs.

5. Maintain a Time Gap Between Consecutive Emails

An ideal time gap between two consecutive emails in an email campaign is 90 seconds since ESP algorithms are based on the fact that no human being can send multiple emails at one go. It’s considered a non-human activity if multiple emails are sent at the exact same time and the emails bounce back. If you’re doing a link-building outreach this will get in the way of building high-quality links.

6. Check Your Sender Reputation Score

A poor sender reputation score causes emails to bounce back or go to the spam folder. This can even have your email account blocked temporarily or permanently. 

Final Thoughts

There could be multiple possible answers to ‘why are my emails bouncing’. This can happen if the email address dooesn’t exist, you misspelt the email id, recipient has blocked you, you emails aren’t authorized, etc.

You can start fixing this by avoiding spam-triggering words, maintaining a time gap between consecutive messages, and deploying SPF, DKIM, and DMARC. Contact our team for a free trial of email authentication services.

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