Fix Domain Exceeded Max Defers and Failures Per Hour Error

Error Message: "Domain has exceeded the max defers and failures per hour (5/5 (100%)) allowed. Message discarded."

This error occurs when your domain has reached the maximum allowed number of deferred or failed email delivery attempts within an hour. The server rejects any further email attempts during this period to prevent potential abuse or spam-like behavior.

This error is common with bulk email sending, newsletter campaigns, or when sending to invalid email addresses.

Key Cause: High Number of Failed Recipients

The main reason for this error is that your email server attempted to send messages to recipients that could not be delivered due to issues like:

Invalid or non-existent email addresses.
Recipient servers rejecting the emails (e.g., due to blacklisting or misconfiguration).
Temporary issues with recipient mail servers.

How to Resolve the Issue

Identify the Cause of Failed Recipients

Check Email Logs

Access your server's mail logs to identify the failed or deferred emails.
For Exim (cPanel):
tail -f /var/log/exim_mainlog
For Postfix:
tail -f /var/log/mail.log

Look for messages like:

"Recipient address rejected."
"User unknown in virtual mailbox table."
"Domain not found."

Use a Reporting Tool

If your hosting provider offers an email statistics tool (e.g., in cPanel or WHM), review the list of failed email attempts and reasons.

Clean Your Email List

Remove invalid or outdated email addresses from your mailing list.
Use an email validation service to verify the validity of email addresses before sending:
- ZeroBounce
- Hunter

Adjust Sending Practices

Reduce Bulk Email Volume: Send smaller batches of emails to avoid hitting server limits.
Throttle Email Sending: Limit the rate at which emails are sent to avoid overwhelming the server or recipient systems.

Check and Fix DNS Configuration

Ensure your domain has proper DNS records configured to avoid rejection by recipient mail servers.

SPF Record:

Authorizes your server to send emails.
Example:
```
v=spf1 include:yourdomain.com ~all
```

DKIM Record:

Adds a digital signature to authenticate your emails.

DMARC Record:

Prevents spoofing and phishing.

Example:

v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com

Use tools like MXToolbox to verify your DNS records.

Test Email Deliverability

Before sending emails to your list, test your email deliverability using tools like:

These tools can detect issues that may lead to email failures.

Contact Your Hosting Provider

Request details about the deferred emails and ask if limits can be temporarily increased.
If the error results from recipient servers rejecting emails, ask your host to ensure their server's IP is not blacklisted.

Monitor and Update Email Sending Scripts

If you're using a custom email-sending script (e.g., for a contact form or marketing tool):

Validate email addresses before sending.
Implement error handling to stop retrying invalid addresses.
Use transactional email services like:

Adjust Server Limits (if You Control the Server)

For WHM/cPanel Servers:

Log in to WHM.
Go to:
Home > Service Configuration > Exim Configuration Manager
Adjust the following:
- Maximum percentage of failed or deferred messages a domain may send per hour: Increase the percentage.
- Maximum number of failed or deferred messages a domain may send per hour: Raise this number.

Prevent Future Issues

Regularly Clean Your Mailing List: Remove unengaged or invalid recipients.
Monitor Bounce Rates: Keep an eye on high failure rates and take corrective action immediately.
Use Reputable SMTP Services: For critical emails, use a reliable SMTP relay service like SendGrid, Mailgun, or Amazon SES.

Error: "Domain has exceeded the max defers and failures per hour (5/5 (100%)) allowed. Message discarded."

Key Cause: High Number of Failed Recipients

How to Resolve the Issue

Identify the Cause of Failed Recipients

Check Email Logs

Use a Reporting Tool

Clean Your Email List

Adjust Sending Practices

Check and Fix DNS Configuration

SPF Record:

DKIM Record:

DMARC Record:

Test Email Deliverability

Contact Your Hosting Provider

Monitor and Update Email Sending Scripts

Adjust Server Limits (if You Control the Server)

Prevent Future Issues

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Error: "Domain has exceeded the max defers and failures per hour (5/5 (100%)) allowed. Message discarded."

Key Cause: High Number of Failed Recipients

How to Resolve the Issue

Identify the Cause of Failed Recipients

Check Email Logs

Use a Reporting Tool

Clean Your Email List

Adjust Sending Practices

Check and Fix DNS Configuration

SPF Record:

DKIM Record:

DMARC Record:

Test Email Deliverability

Contact Your Hosting Provider

Monitor and Update Email Sending Scripts

Adjust Server Limits (if You Control the Server)

Prevent Future Issues

Hosting

Cloud Solution

For You

VDS

Website Builders

Our services

Client Area

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