"Your email couldn't be delivered." Again. But why?
Even when you believe you've set everything up properly, there are numerous reasons why your email might not get delivered. This issue is commonly called a bounce, which occurs when an email fails to be delivered to the recipient's email server.
For email marketers, bounces can be a significant problem, as they reduce the delivery rate and negatively impact the performance of campaigns.
While some delivery issues may arise due to your own actions, more often than not, the causes are beyond your control. In this guide, we will explore the different types of bounces and how to check your campaign's bounce rate using Mailmodo's analytics dashboard.
What are hard bounces and soft bounces?
Based on reasons for bounce, bounces can be divided into two categories - hard bounces and soft bounces.
Hard bounce
A hard bounce refers to a permanent issue that prevents an email from being delivered. Issues that lead to hard bounces include:
Invalid or non-existent email address (e.g., e.g., Jonh@gmail.com, instead of [John@gmail.com](mailto: John@gmail.com)). It may also happen when someone permanently deactivates his/her account, especially due to a job change.
The recipient's email server has completely blocked delivery from the sender server.
When an email hard bounces, it usually indicates that the email will never be successfully delivered to that address in the future. Email servers usually stop attempting delivery for emails that hard bounce to maintain the sender reputation and email deliverability.
Here’s what an email failure notification would look like if you are blocked by the recipient.
In the context of email bounces, you'll often receive notifications from "Mailer Daemon", an automated system that informs you of delivery issues. When your email fails to deliver, the recipient's server triggers a Mailer Daemon response detailing the bounce (hard or soft) and the reason for failure. These messages help you identify and resolve email deliverability challenges.
Soft bounce
A soft bounce is a temporary failure in the delivery of an email, and you might be able to send an email to the same email address later.
Issues that lead to soft bounces include:
The recipient's mailbox is full.
The recipient email server is down or offline.
The email message is blocked due to content.
The email message is too large.
The email server is facing an overload issue.
The email doesn’t meet the recipient server’s anti-spam and antivirus requirements.
Try sending emails to these addresses after resolving the errors and check the email delivery rate. If, even after many further attempts, emails are getting bounced, then it's good to put such addresses in your suppression list.
Mailmodo retries the delivery of a soft bounced email again after two days before sending it back to the sender. Read how SBNRI managed their suppression list with Mailmodo, leading to a 16% increase in open rates.
Hard bounce vs soft bounce
Summed up are all the main differences between hard bounces and soft bounces.
| Aspect | Hard Bounce | Soft Bounce |
|---|---|---|
| Failure type | Permanent delivery failure | Temporary delivery failure |
| Error codes | Typically 5xx SMTP error codes (e.g., 550) | Typically 4xx SMTP error codes (e.g., 421, 450) |
| Action required | Remove from list and make no further delivery attempts | Retry delivery after error resolution or later |
| Sender reputation impact | Negative, affects sender credibility | Minimal, if managed promptly |
| Frequency | Usually occurs consistently for the same addresses | May occur for any email address due to temporary issues |
| Failure handling | Emails return to sender once they bounce | Email servers retry delivery before sending it back to sender |
How to know an email has bounced
When an email bounces, the sender usually receives a bounce message. Here’s how the sender learns that the email has bounced:
1. Bounce notification: The sender's email server receives a bounce notification from the recipient's email server indicating the delivery failure.
2. Email analytics dashboard: Many email service providers (ESPs) provide a dashboard where users can view their campaign performances and bounce reports. This dashboard gives details about the open rate, bounce rate, unsubscribe rate, etc., and the reasons for bounce. Given below is a picture of the analytics dashboard in Mailmodo.
Where to find email bounce information in Mailmodo
Mailmodo has an extensive analytics dashboard that gives you insight into the performance of your email marketing campaigns by displaying different email metrics.
Following are the steps to check email bounce information.
Step 1: Log in to your account.
Step 2: Select the campaign you want to track. The analytics dashboard will open.
This is a snapshot of Mailmodo's analytics dashboard showing bounces and blocked.
Bounces: The number of contacts who did not receive the campaigns due to non-existent email addresses, recipient's full inbox, or other reasons.
Blocked: The number of contacts that were not sent the campaigns because they unsubscribed or got bounced in the past.
To get in-depth information about the blocked and bounced email addresses, go to “User data”, and you'll see the following details for all the email addresses you’ve sent the campaign:
Bounced email addresses, reason, and time
Blocked email addresses, reason, and time
Other additional metrics like unsubscribed, opened, clicked etc.
Once you have this data, you can fix the issues that are causing the bounce put these email IDs in the suppression list, and stop sending them in the future if needed.
Besides, Mailmodo takes the following actions when the bounce rate surpasses the given limit:
For email bounce rates higher than 3%, we will warn you that your account will be banned from Mailmodo if the rate goes above 5%.
If your bounce rate is higher than 5%, your account will be banned permanently, and you will not be allowed to send any more campaigns using Mailmodo.
Check out our analytics help guide to know in detail.
Send Emails with Greater Deliverability
Conclusion
Understanding and managing hard and soft bounces is essential for maintaining a healthy email reputation. By diligently categorizing and addressing bounce types, you can significantly improve your email deliverability and overall campaign performance.
Remember, a lower bounce rate means a higher chance of your emails reaching the intended subscriber list, leading to better engagement and ROI. At Mailmodo, we ensure that our clients' bounces are the lowest and that bounce suppression is readily available to improve the campaigns. If you like to learn more about this, please reach out to the Mailmodo team.
