Business Mail 101

When sending bulk mail, it's important to know which mail classification your mailpieces fall into. Here are some basic rules of thumb for letters, flats and parcels.

To qualify as a letter, a mail piece must range from 3 1/2" x 5" to 6 1/2" x 11 1/2". This category usually includes postcards, letters (inserted into envelopes), and newsletters (folded to appropriate size and tabbed).

A flat, also referred to as a large envelope, must range between 6 1/8" x 11 1/2" and 12" x 15" to quality as First-Class Mail. The thickness must also be between 1/4" and 3/4". Flats cannot be rigid or any shape other than a rectangle. Newsletters and magazines also quality as flats.

Letters that weigh more than 3.5 ounces, or are thicker than ¼ of an inch, are not eligible to be presorted as letters and will qualify as flats. PPS can presort your flats if postage is not applied, and we will invoice you for the postage. If you apply postage to your flats and parcels, you must apply the full rate postage.

If your mailpiece does not classify as a letter or a flat, then it is a parcel. While typically slower to ship, parcels offer great cost savings.

Depending on the size, there are generally three types of parcels:

  • Commercial Parcels - Commercial parcels must be at least 3” high x 6” long x ¼” thick. Unless it falls under Standard Post and Parcel select, the mailpiece cannot be weigh more than 70 pounds, and must measure less than 108” in length and girth (thickest part) combined.

  • Machinable Parcel - A parcel is considered “machinable” when it is prepared to be processed on Postal Service equipment. A machinable parcel cannot measure more than 27” long x 17” wide x 17” high. It cannot exceed 25 pounds. For Parcel Select and Parcel Return Service, it can weigh no more than 35 pounds. Books and other printed material must weigh 25 pounds or less.

  • Balloon and Oversized Parcels - If your parcel does not qualify as a commercial or machinable parcel, please contact us. It may be subject to specialized prices.