When the weight of your envelope or parcel exceeds the 13 ounce limit for First-Class mail, you can utilize the USPS Priority Mail service. Priority Mail allows you to send mail based on weight and dimension or via flat rate envelopes or boxes in a fast and affordable way. Priority Mail includes tracking and delivery in 1-3 business days. You can enable Priority Mail in e-Certify in your Company settings. To create a piece of priority mail, follow the instructions in the detailed documentation below.