Domain (example.com) has exceeded the max defers and failures per hour
If you are receiving an error similar to “Domain example.com has exceeded the max defers and failures per hour (5/5 (100%)) allowed” in an email bounceback, it means that outgoing email from your domain has triggered a rule in the server that will stop any further email from going out of the server.
This happens when a domain account sends out emails that either fail or get deferred by the recipients mail server. Failures can come in the form of an unknown user to too many connections from your IP. If the number of failures or defers are greater than the server limit, no further mails are allowed.
What does this error(max defers) mean?
If you are receiving an error similar to “Domain example.com has exceeded the max defers and failures per hour (5/5 (100%)) allowed” in an email bounceback, it means that outgoing email from your domain has triggered a rule in the server that will stop any further email from going out of the server until the next hour. This happens when a domain or cPanel account sends out a number of emails that either failed or deferred within the last hour.
If the number of failures or defers exceeds the server limit, no further emails will be processed.
The blocked domains can send emails again at the top of every hour. For example, if you received this error at 1:15 pm, the block will release at 2:00 pm, and the domain will be able to send emails once more unless the messages keep deferring; you’ll trigger that error again until the message is delivered, or the server stop retrying to send a deferred message.
What is a deferred message(max defers)?
A deferred message is the message that the recipient serves didn’t accept from the first time and rather returned a temporary failure. This technique is used by some email servers to mitigate spam messages since most spammers won’t retry to send a deferred message.
How?
The default limit is typically sufficient for the majority of users. If you or your users are exceeding this limit then you may need to contact technical support to monitor your email usage and determine if it’s a malware issue (automatic email scripts) or if it’s simply a usage issue with you or your users. If you’re on a VPS or dedicated server you can monitor this yourself in WHM, but a Business level host (shared hosting) will require that you request support to do this for you.
Why?
Our email servers use a limit on outgoing email because high levels can result in the server being blacklisted and flagged as sources of spam. This would result in your server being unable to deliver email to multiple recipient servers. You can request an increase in the limit, but it will be limited on shared hosting servers.
If you want more control over this, then you should be on a VPS or Dedicated server account. However, you will be held responsible for the reputation of your account. Continually outputting thousands of emails for marketing purposes can result in your account being blacklisted by recipient servers. Regular problems with this would then be your responsibility for working to get the server de-listed (for VPS and Dedicated server accounts).
Prevention of max defers
To prevent max defers and failures per hour error messages please check the following:
Ensure your account is not sending spam. Check your mail delivery reports in your cPanel > Track Delivery. If you see a large number of delivery failures from one of your email addresses then we recommend immediately changing your mailbox password and virus scanning all your devices.
Check autoresponders and spam filters. This block can sometimes be triggered when you have an autoresponder setup to send an out-of-office reply to all emails you receive. This is because the autoresponder will reply to all emails including spam email addresses which do not exist. In these cases the reply will fail which counts towards the delivery failure count per hour on your domain. To resolve this ensure your Spam Filters are enabled on your cPanel account. This will ensure emails we flag as spam are not sent an autoresponse.
Check your mailing lists is up to date. If you are sending a mass marketing email, please check your mailing list is up to date by removing email addresses which no longer work. Sending to multiple invalid email addresses will trigger the block. The only way to resolve this is to clean your mail list and remove email addresses which result in bouncebacks.
If you do not know exactly what is causing it, you can probably find out by using the Track Delivery icon in your cPanel.
When you click on the Track Delivery icon, a field appears where you can enter the recipient’s email address. Then click on the “Run Report” button to get information about the emails sent to this recipient.
If you do not enter anything for the recipient’s email address, you will be able to retrieve the data for all email traffic.
You will then see groups of returned messages that can help you determine which sender caused the problem and why.
What should you do to prevent/fix this max defers issue?
There are two circumstances in which this will happen:
If you send mass emails
If you send a mass/huge emails and this happens, it probably means that some of your subscribers are no longer using the email addresses they subscribed to.
You will need to clean up your mailing list and stop sending emails to these inactive accounts.
The Track Delivery tool in your cPanel, which will help you identify inactive emails and clean up your mailing list.
If you do not send bulk emails
If you do not send mass emails but receive the “max defers and failures per hour” bounce message, it may mean that your account has been hacked.
Before you panic, follow the steps above to identify recently sent emails from your account.
If you do not recognize most of the email addresses in the Email Tracking report, you must update the email account password used to send these emails.
You will also need to put a captcha on the sending forms on your site.
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