Diagnosing And Resolving Email Delivery Failures

Modified on Thu, 02 Feb 2023 at 07:38 PM

Email campaigns are a powerful tool for reaching a large audience, but they can also be subject to various delivery failures that can negatively impact their effectiveness. 

When an email campaign fails to reach its intended audience, it's important to investigate the cause of the problem in order to prevent it from happening again in the future. This process of investigating email delivery failures can be complex, involving a variety of factors such as spam filters, invalid or inactive email addresses, list hygiene, IP or domain reputation, authentication, email content, mailbox full, blocked by the firewall, over-sending, and many more.

Email Sent Is Less Than Target Audience

Before exploring the reasons for an email campaign's failure, let us examine a common scenario where you may have sent an email, but the actual number of emails sent was lower than the intended target. This is commonly referred to as email discard.



In an email campaign, a discard can occur due to various factors explained below, such as invalid or inactive email addresses, duplicate email addresses in the list, emails unsubscribed from the list, and campaign restrictions like DND, Frequency Capping, Control groups, etc.

Investigating these issues is important in order to understand the cause of reduced email delivery count and to consequently take appropriate actions to improve the deliverability rate.

Now, let's explore the most common types of email delivery failures in bulk campaigns, along with strategies for identifying and resolving these issues to improve deliverability rates and ensure your messages reach the intended audience.

Failure To Send Email

In the event of an email not being sent, it's important to investigate the issue to ensure successful delivery. One way to start this investigation is by checking the email failures in the email statistics for a specific campaign. 

To access this information, navigate to 'campaigns' from the left panel, select 'email', and click on the specific campaign name. In the 'email stats' tab, you'll be able to see the total number of email failures. This number represents the number of emails that were unsuccessful in being sent.



Understanding the reason for the failures is crucial in resolving the issue and ensuring successful email delivery in the future. Common causes of email failure are:

1API Credentials Are Incorrect

API credentials are the login information (username, password, key) that is used to access an API. In case the API credentials of an email service provider are incorrect, then such an occurrence can prevent an application from sending emails via the API.

Investigation: This can be investigated by checking if the credentials are entered correctly and if the account is still active. Additionally, it's important to check if the account has the correct permissions to access the email API.

Solution: If the credentials are found to be incorrect, it is necessary to update or correct them in order to send emails via the API successfully. Not having access to the correct credentials will result in an error message, and the email won't be sent. It's important to keep these credentials updated and secure.

2. Vendor Panel Credits

Vendor panel credits refer to the available balance of email-sending capacity that a vendor has. If the vendor panel credits are not available for sending emails, it means that the vendor has reached their limit of emails that can be sent or the account balance is insufficient. 

Investigation: If the vendor panel credits are not available for sending emails, it is important to take steps to determine the cause of the issue. This can include checking the vendor's account balance to see if there is insufficient funds, reviewing the daily or monthly email sending limits to see if they have been reached, or reaching out to the vendor's support team for further assistance. By taking these steps, the vendor can gain a better understanding of the issue and take appropriate action to resolve it, such as purchasing additional credits or waiting until the next billing cycle to have more credits available.

Solution: Based on the investigation above, if you find that your credits are insufficient, you may need to purchase additional credits or wait until the next billing cycle to have more credits available. It is important to keep track of your email credits to ensure that there are sufficient credits available for sending emails, or for ease of sake, you can turn on the auto-renew option. This option will automatically add credits to your account when your monthly credit balance is less than 80%.

Low Delivery Rate Because Of Bounced / Rejected Emails

Bounced emails are emails that are returned to the sender because they could not be delivered to the recipient's mailbox. Bouncing occurs when an email message cannot be delivered to its intended recipient. 

There are two types of bounced emails: soft bounce and hard bounce. A soft bounce is temporary and is caused by issues such as a full mailbox or a server being temporarily unavailable, while a hard bounce is permanent and is caused by a non-existent email address or a domain that is blocked. 

To view information on your bounce rate, follow these steps: Go to 'campaigns' section on the left panel, choose the 'email' option, select the specific campaign name, and then navigate to the 'email stats' tab. Here, you'll find the total number of emails that bounced.



Bounced emails can have a detrimental effect on the sender's email deliverability and reputation, so it's essential to identify the root cause and take corrective measures.

1. Invalid Or Inactive Email Addresses 

Invalid or inactive email addresses can negatively impact the deliverability of an email campaign. When an email is sent to an invalid or inactive address, it will result in a bounced email. This can damage the sender's reputation and decrease the overall deliverability rate.

Investigation: To investigate why emails are bouncing due to invalid or inactive email addresses, you can start by analyzing your email list and checking for any invalid or inactive email addresses. You can also use email verification tools to validate email addresses before sending the campaign. Another thing you can do is conduct a re-engagement campaign; this can help you to identify inactive email addresses from your list. 

Solution: Based on the findings above, you can take necessary actions to improve your IP or domain's reputation, such as adhering to email best practices, maintaining a clean email list, and monitoring your campaigns' performance.

2. Blocked By Firewall

Corporate firewalls are security systems that are used to protect an organization's network from unauthorized access. These firewalls can block incoming emails from certain IP addresses or domains. If an email is sent from an IP address or domain that has been flagged as a potential security threat or if it contains certain types of attachments (files with untrusted sources, archive files, executable files, etc.) or URLs (shortened URLs, links to untrusted websites or from unauthenticated sources, etc.), it may be blocked by the corporate firewall. This can negatively impact the deliverability of an email campaign. 

Investigation

To investigate email blocking by corporate firewalls, 

 check the IP address or domain for any security threats, 

 check bounce rate and recipients marking emails as spam, 

 examine email content for attachments or URLs that may trigger the firewall,

 check if the email is sent from a shared IP or domain with a poor reputation, 

 contact the recipient's IT team to whitelist your IP and domain.

Solution: It's important to ensure that the IP address or domain used to send emails is not flagged as a potential threat and to avoid including certain types of attachments or URLs mentioned above that may trigger the firewall.

3. Sending To A Purchased List

Sending to a purchased list refers to sending emails to a list of email addresses that you have obtained from a third party. This can result in a high number of bounces and unsubscribes because the recipients may not have opted in to receive emails from you. This can negatively impact the deliverability of your email campaigns and may lead to poor engagement and low ROI. 

In this case, our suggestion is to only send emails to opt-in lists and avoid using purchased lists to ensure good deliverability and engagement. If, for some reason, you still want to use a purchased list, and want to avoid email bounce backs, then identify the root causes first and then apply solutions accordingly as mentioned below.

Investigation: To investigate why emails are not being delivered or engaged with when sent to a purchased list, you can start by analyzing your email list and checking for any invalid or inactive email addresses. Additionally, you can check the bounce rate and the number of recipients marking your emails as spam.

Solution: To avoid this, you can also use email verification tools to validate email addresses before sending the campaign. Also, you can segment your list and send targeted emails based on the recipient's engagement history and preferences.

Emails Delivered But Not Showing In Mail Inbox

Emails sent to spam refers to the emails that are marked as unwanted or junk by the recipient's email service provider, and are sent to the recipient's spam folder instead of their inbox. Here are the various reasons why an email is sent to spam.

1. Spam Filters 

Spam filters are used to block unwanted emails from reaching a recipient's inbox. Emails can be blocked by spam filters at the recipient's email service provider or at the organization's own spam filter. This can negatively impact the deliverability of an email campaign if the emails are perceived as spam or unwanted. 

Investigation: To investigate why emails are getting blocked by spam filters, analyze the email content, subject line, and the sender's reputation, checking if there are any trigger words or phrases that are causing the emails to be marked as spam.

Solution: To prevent this, it's important to ensure that the content of the emails is relevant, engaging, and adds value to the recipients. Avoid using certain trigger words or phrases that can trigger spam filters, and make sure the content is not perceived as spam or unwanted.

2. IP Or Domain Reputation

The IP address or domain used to send an email campaign can play a crucial role in the deliverability of the emails. If the IP or domain has a poor reputation, it can result in the emails being blocked or marked as spam by the recipient's email service provider. This can happen due to various reasons, such as previous spam complaints, high bounce rates, or low engagement. A poor reputation can also be caused by other users on a shared IP or domain who have poor sending practices. 

Investigation: To investigate why emails are being blocked or marked as spam due to poor IP or domain reputation, you can start by monitoring your IP or domain's reputation. There are various tools and services that can help you to check the reputation of your IP or domain, such as SenderScore, Barracuda Reputation System, and many more. 

Additionally, you can check your email service provider's sending reputation and see if there is a pattern of high volumes of emails being marked as spam. Another thing you can do is to check if the IP or domain is being used by other users who have poor sending practices, which can negatively impact the reputation.

Solution: In order to ensure high deliverability rates, it's important to maintain a good reputation by adhering to email best practices and monitoring your IP or domain's reputation.

3. Authentication

Authentication is a process to verify the identity of the sender of an email. The most common methods of email authentication are SPF, DKIM, and DMARC. These protocols help to ensure that the email is not coming from an unauthorized sender and that it hasn't been tampered with during transit. Lack of proper authentication can cause emails to be marked as spam, as it may be seen as a potential phishing or spam attempt. 

Investigation: To investigate email authenticity issues caused by improper authentication, check email headers for authentication methods used, verify DNS records for correct SPF, DKIM, and DMARC setup, and use email authentication tools to validate email authenticity. 

Solution: Take necessary actions to improve email authentication, such as setting up proper authentication protocols and ensuring DNS records are correct.

4. Email Client Compatibility

Email client compatibility refers to the ability of an email to be properly displayed and interacted with across different email clients or applications. 

Some email clients may not support certain types of email content, such as images, videos, or certain formatting, which can affect engagement and deliverability. This can lead to recipients not being able to view the email as intended and may lead to poor engagement and deliverability. 

Investigation: To investigate this, you can check the open and click-through rates, as well as the number of unsubscribes or spam complaints. Another thing you can do is to conduct a survey of your recipients and ask for their feedback on the compatibility of the emails and if they find them displayed properly and convenient to interact with.

Solution: Test the email's compatibility across multiple email clients to ensure that it is properly displayed and interacted with. Based on the findings, you can make necessary changes to your email content, subject line, and sender's reputation to ensure that it is properly displayed and interacted with across multiple email clients and to avoid poor engagement and deliverability.

5. Over-sending

Sending multiple emails in a short period of time can cause recipients to mark the emails as spam or unsubscribe from the list. This is known as over-sending. When recipients receive too many emails in a short period of time, they may feel overwhelmed and start to ignore or delete them without reading. Additionally, if recipients mark an email as spam, it can damage the sender's reputation and make it harder for future emails to reach the inbox. 

Investigation: To investigate over-sending issues, you can start by analyzing your email sending schedule and the number of emails sent in a certain period of time. You can also check the recipient's engagement with your emails, such as open and click-through rates, as well as the number of unsubscribes or spam complaints.

Solution:  To avoid over-sending, it's important to limit the number of emails sent in a short period of time, segment the list and send targeted emails based on the recipient's preferences and engagement history.

These are the most common email troubleshooting issues faced by users in a bulk campaign. Hope we are able to cover the ones you are facing. If you're looking for a comprehensive analysis of your email campaign, kindly check out our article 'Email Campaign Report Analytics' by clicking here.

Conclusion

In conclusion, diagnosing and resolving email delivery failures in a bulk campaign is crucial for the success of any email marketing strategy. However, it's worth noting that email deliverability is a complex and dynamic process. It's a combination of several factors that could change over time, and it's an ongoing effort. 

Therefore, it's essential to stay up to date with the best practices and latest trends in email marketing and to continuously monitor and optimize your email campaigns to ensure high deliverability rates. 

Ultimately, by diagnosing and resolving email delivery failures, you can improve your email campaign's effectiveness, increase customer engagement and drive better business results.

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