Possible causes of "Max defers and failures" error on cPanel and how to identify the root cause of it?

What does "Max defers and failures error" mean?

If you see an error like "Domain example.com has exceeded the max defers and failures per hour (5/5 (100%)) allowed," it means that your email server has a rule triggered because your domain's outgoing emails are encountering issues. This occurs when emails from your domain either fail or are delayed by the recipient's mail server. Failures can be due to reasons like sending to an unknown user or too many connections from your IP. If the number of failures or delays surpasses the server limit, it stops any more emails from being sent.

What are the possible causes of "Max defers and failures" message on cPanel server?

The "Max defers and failures" message on a cPanel server typically indicates that the server has reached a limit on the number of deferred or failed email messages within a specific time frame. Several factors could contribute to this situation. Here are some possible causes:

Sending to Invalid or Non-existent Email Addresses:

If the server is attempting to send emails to invalid or non-existent addresses, it can result in failures or deferrals.

Exceeding Sending Limits:

The server may have predefined limits on the number of emails that can be sent per hour or restrictions on the percentage of failed or deferred messages.

Bulk Email Sending:

Sending a large volume of emails, especially marketing emails, from a single domain may trigger these limits.

Issues with Recipient Mail Servers:

Continuous failures or deferrals due to problems with the mail servers of the recipients can contribute to the issue.

Spam-Related Activities:

The server may be flagged for spam-related activities, either due to the content of the emails or the behavior of the server.

Issues with Email Content:

Content within the emails, such as attachments or certain keywords, may trigger spam filters, resulting in failed or deferred messages.

Identifying the specific cause of the "Max defers and failures" message requires reviewing server logs, examining bounce messages, checking email configurations, and monitoring the behavior of outgoing emails. By investigating these factors, administrators can determine the root cause and take appropriate actions to resolve the issue.

Steps we need to follow to identify the root cause of Max defers and failures error:

Identifying the root cause of the "Max defers and failures" error on a cPanel server involves a systematic investigation. Here are steps you can follow to pinpoint the issue:

Check Email Logs:

Examine the email logs on the cPanel server. These logs often provide detailed information about deferred or failed email messages. Look for patterns, error messages, or specific accounts/domains causing issues.

Use Track Delivery Tool:

In cPanel, use the "Track Delivery" tool to gain insights into the delivery status of emails. This tool allows you to see the delivery route and identify any specific emails or domains experiencing problems.

Review Bounce Messages:

Analyze bounce messages received for failed email deliveries. Bounce messages typically provide information on why an email failed to be delivered, helping you identify the root cause.

Check Mail Queue:

Inspect the mail queue on the server. Identify any stuck or pending email messages that might be causing delays or failures.

Monitor Outgoing Email Traffic:

Keep an eye on outgoing email traffic, especially during peak times. Unusually high volumes may indicate potential issues. Check if there is a sudden surge in email activity.

Review Email Content:

Examine the content of the emails being sent. Certain content may trigger spam filters or result in delivery issues. Ensure that the emails comply with standard practices.

By systematically going through these steps, you can identify the root cause of the "Max defers and failures" error and take appropriate actions to resolve the issue, whether it involves adjusting server configurations, addressing specific email content issues, or mitigating potential security threats.

How can we fix this?

-> This error happens because of a system that checks blocked domains every hour. If your domain is blocked, it can send emails again at the beginning of the next hour. For instance, if you got the error at 2:45 pm, the block will be lifted at 3:00 pm, and your domain can send emails again.

-> Remove the email addresses that are causing issues, and the rest will be sent successfully. In cPanel, you can use the Track Delivery tool. Before the 5/5 Message discarded errors, there will be other sending failures, mainly because of incorrect recipient addresses. These failures led to the temporary block.

-> Double-check that you're sending emails to the right address to prevent spelling mistakes.

-> Read bounce messages to catch and fix any obvious errors.

-> If you need to send mass emails, consider using a third-party service, as this product is not meant for such use.

-> See if your email account has used up its storage space. If it has, you can add more space by logging into your cPanel account. Here's how:

1. Log in to your cPanel.

2. Go to Email Accounts.

3. Select the email account that has reached its limit and click on Quota.

4. Either set a specific number for your Mailbox Quota or choose Unlimited, then click Update Email Settings.


By diligently following these steps, administrators can pinpoint the specific issues contributing to "Max defers and failures" messages on a cPanel server. Addressing these root causes not only resolves the immediate problem but also fortifies the server against future disruptions, ensuring a robust and dependable email delivery system.

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