Identify the envelope sizes, paper weights, flap styles, and thicknesses received most often. Standard business envelopes are usually straightforward, but padded mailers, unusually thick pieces, and envelopes containing bulky inserts may require another opening method. The machine’s stated envelope range should cover the smallest and largest formats used regularly. Mixed-mail feeding is valuable when staff do not have time to sort every batch by size. A sample using actual incoming mail can reveal whether curled edges, overfilled envelopes, or uneven stacks affect feeding. Selecting equipment around real mail characteristics helps reduce missed pieces, envelope jams, and accidental damage to the contents.