From the FTC's web site.
http://business.ftc.gov/documents/bus02-business-guide-mail-and-telephone-order-merchandise-ruleWhat is the Mail or Telephone Order Rule?
The Rule requires that when you advertise merchandise, you must have a reasonable basis for stating or implying that you can ship within a certain time. If you make no shipment statement, you must have a reasonable basis for believing that you can ship within 30 days. That is why direct marketers sometimes call this the "30-day Rule."
What You Must Do If You Learn You Cannot Ship on Time
When you learn that you cannot ship on time, you must decide whether you will ever be able to ship the order. If you decide that you cannot, you must promptly cancel the order and make a full refund.
If you decide you can ship the order later, you must seek the customer’s consent to the delay. You may use whatever means you wish to do this -- such as the telephone, fax, mail, or email -- as long as you notify the customer of the delay reasonably quickly. The customer must have sufficient advance notification to make a meaningful decision to consent to the delay or cancel the order.
What a First Delay Option Notice Must Say
In seeking your customer’s consent to delay, the first delay notice you provide to the customer (the "delay option" notice) must include:
a definite revised shipment date or, if unknown, a statement that you are unable to provide a revised shipment date;
a statement that, if the customer chooses not to wait, the customer can cancel the order and obtain a full and prompt refund; and
some means for the customer to choose to cancel at your expense (e.g., by providing a postage prepaid reply card or toll-free telephone number).
the following information when you cannot provide a revised shipping date:
the reason for the delay, and
a statement that, if the customer agrees to the indefinite delay, the customer may cancel the order any time until you ship the merchandise.
If your first delay option notice provides a definite revised shipping date of 30 days or less, you must inform customers that their non-response will be treated as a consent to the delay.
When You Must Cancel an Order
You must cancel an order and provide a prompt refund when:
the customer exercises any option to cancel before you ship the merchandise;
the customer does not respond to your first notice of a definite revised shipment date of 30 days or less and you have not shipped the merchandise or received the customer’s consent to a further delay by the definite revised shipment date;
the customer does not respond to your notice of a definite revised shipment date of more than 30 days (or your notice that you are unable to provide a definite revised shipment date) and you have not shipped the merchandise within 30 days of the original shipment date;
the customer consents to a definite delay and you have not shipped or obtained the customer’s consent to any additional delay by the shipment time the customer consented to;
you have not shipped or provided the required delay or renewed option notices on time; or
you determine that you will never be able to ship the merchandise.
Filing a complaint with the FTC
https://www.ftccomplaintassistant.gov/FTC_Wizard.aspx?Lang=en