If you receive a message that looks like this:
"Domain has exceeded the max defers and failures per hour (8/10 (80%)) allowed. Message discarded."
That means - at least 70% of the emails you sent out during the past 60 minutes were addressed to invalid or mis-typed or non-existent recipients. (Or in some cases, even recipients that have blocked messages from you).
This is one of the important security functions of our mail servers - it's main purpose is to help prevent spam attacks from your account when, for example, if your password were to be compromised or an infection on your computer attempts to send out a bunch of spam without your knowledge.
If more than 70% of the emails you send out within a 60 minute period are addressed to invalid recipients as described above, then the mail server will send you that alert and prevent mail from being sent from your account for the remainder of that 60 minute period.
EXAMPLES OF HOW THIS CAN HAPPEN:
First example - if you send out an email to 10 recipients and 8 of those bounce back to the server due to 8 of the recipient addresses being non-existent, the server detects that more than 70% of your outgoing emails are to bad recipients and it will trigger this security feature, and you won't be able to use email on the domain for 60 minutes (unless you contact us to have the block manually removed).
If you are encountering this in a scenario where you've sent a message to a group of people then you know it's time to clean-up your contacts list and weed-out the invalid recipients whose email addresses no longer exist.
Second example - if you have created a Forwarder email address that is forwarding to an account that you have at a service such as Gmail or Hotmail or Yahoo, and the address that you have forwarded is receiving a large amount of spam or bounced emails, then the service you have Forwarded email to may also "defer" those messages or "fail" them, sending a signal back to your mail server here which can trigger the max defers and/or failures limit.
Another important thing to take into consideration - since we do not allow bulk promotional mailings here (to help prevent our mail servers from being blocked by other ISP's), if you have a need to send out mailers to large numbers of recipients on a regular basis, you should definitely check into one of the many mailing list / newsletter solution providers out there. The one we currently recommend most is http://www.ymlp.com since they offer a free service that is extremely easy to use and feature-rich. In fact, using ymlp.com to set up your mailers and newsletters will also automatically detect any non-existent recipients / bad email addresses in your list and report them to you so that you can remove them from your list!
IN ALL CASES - If you receive that warning message and you have not sent out the emails, then you should contact us immediately to try to determine the source of the problem.
