Bulk mail is a way to save money on postage by doing things that save the US Postal Service (USPS) money. They pass some of the savings along to you by charging you lower postage prices.

The most common type of bulk mail is called "Standard Class". (It used to be called "3rd Class".) Most advertising mail, newsletters, etc. are sent using Standard Class.

To use Standard Class, your pieces must be essentially identical, without any personal information. That means you can't scribble notes to your friends on various pieces. It also means you can not send invoices, statements, and other individual information using Standard Class.

However, you may send form letters on which you personalize the name and address, so long as the rest of the letter is the same for everyone. If you send more than 500 invoices, statements, or similar mail at one time, you may apply for discounted presorted First Class Mail.