Max defers and failures per hour error for cPanel email

If an email from a cPanel email account bounces back saying your domain has exceeded the max defers and failures per hour, our mail server has temporarily stopped your domain from sending email because too many of its recent messages failed. Sending resumes automatically, usually within an hour, so you don’t need to contact us to lift the block. To stop it from happening again, fix whatever caused the failed messages.

Cause

We limit failed messages to stop spam and keep our mail servers off spam blocklists, so your email keeps reaching inboxes. When your domain has 5 failed or delayed messages within an hour, we pause all outgoing email from every cPanel email account on your domain.

When this happens, you get a bounce-back message like the following:

This message was created automatically by mail delivery software.

A message that you sent could not be delivered to one or more of its
recipients. This is a permanent error. The following address(es) failed:

  [email protected]
    Domain yourdomain.com has exceeded the max defers and failures per hour (5/5 (100%)) allowed. Message discarded.

The 5/5 in the message means your domain has reached the limit of 5 failed or delayed messages.

You can still receive email during the block. Don’t resend messages until it lifts, because they’re discarded and can keep your domain blocked for longer.

Solution

Check the bounce-back messages in your inbox from the hour before the block and then use the fix that matches what they show. The following table lists the most common causes first:

Bounce-backs show	Cause	What to do
The address doesn’t exist, such as unknown user or no such user	Misspelt or old recipient addresses	Correct or remove each address in your contacts or mailing list. To send newsletters to a large list, use an email marketing service.
Forwarded messages you didn’t write	A forwarder that sends your email to an outside mailbox, such as Gmail	Delete the forwarder. To learn how to delete, read the How to set up email forwarding in cPanel.
Messages you didn’t send	A compromised email account or website	Change your cPanel email passwords straight away, as the following important notice describes.
Automatic replies to addresses you don’t recognise	An autoresponder replying to spam	Turn off the autoresponder you've set up for your email account.
Spam, policy, or authentication	Recipients’ mail servers treating your email as spam	Add SPF, DKIM, and DMARC records to your domain. See Set up SPF, DKIM, and DMARC records for cPanel email.
The mailbox is full, or the server is unavailable	A problem with the recipient’s mailbox	Wait a few hours before you email the recipient again.

Important: If you get bounce-backs for messages you didn’t send, or contacts tell you they’ve received spam from your address, change the password for each cPanel email account on your domain straight away. For the steps, see Change your email password article title.

After the block lifts, resend the messages that bounced.

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