The Issue:

I'm trying to send out email and i'm receiving bounceback messages that contain the following line:

Domain mydomain.com has exceeded the max defers and failures per hour (#/# (100%)) allowed. Message discarded.

(where mydomain.com is your actual domain name and # represents the number of failures for the hour)

What is the cause of this?

The mail server will limit sending capabilities for any domain receiving a high number of deferred (mail that was unable to deliver to the sender and has been added to the servers mail queue) or failed emails (a message that failed to reach its recipient), as this is almost always an indication of spam going out from the domain. However, there are a few other reasons why you may be receiving these types of bouncebacks. Please see below.


1) You have an auto responder set up that is replying to spam email addresses that don't exist.

2) You have a mailing list setup with emails address that no longer exist.

3) Your email address may have been compromised and is being used to send spam.

What do I need to do?

The max defer limitation is reset every hour, however, if the mail server continues to receive deferred or failed bounceback emails originating from your domain name, you will continually trigger that setting. This is why it's important to address the issue right away to guarantee you don't run into problems again in the future.

1) If you have an auto-responder setup, try removing the auto-responder and see if the issue clears up.

2) If you have a mailing list setup, pay close attention to any bounce back emails you are seeing come back after your mailing goes out and remove the problem email accounts from your list. Some mailing lists will manage bounced emails for you, however, we suggest you also do a manual check.

3) If you believe your hosting account or email address has been compromised and is being used to send spam, you will want to change your password(s) right away to prevent further spam from going out.