What is the "Not sufficient credit balance. Please buy more credit and try again. Thanks!" error message?

If you receive this error message:

Not sufficient credit balance. Please buy more credit and try again. Thanks!

Your user credit balance is not enough to process your order. You will have to buy additional user credit. If you are submitting jobs via Batch, MailJack+, Email to Mail, or one of our other applications, we will be able to restart your jobs without requiring a resubmit. Jobs can only go on hold for this reason for 48 hours. After 48 hours, we are no longer able to restart the jobs.