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Proper envelope construction

It’s important that your envelopes are constructed properly to ensure best performance in our automated equipment.


To make sure we smoothly process your envelopes we recommend that the back panel of your envelope cover the side flaps.

If you construct your envelopes in such a way that you cover the back panel with the side flaps, then follow the illustrated sealing requirements shown in the following illustrations:

Option 1

An example of an envelope with the back panel covered by the side flaps

Option 2

Another example of an envelope with the back panel covered by the side flaps


Most self-mailers are created from a single piece of durable paper or cardstock, which is folded into panels and secured with adhesive tabs or glue spots to keep it tightly closed during transit.

Single sheet

For the best processing, clip or spot seal the right and left edges of the self-mailer in addition to the top.

Fold-over self-mailers may have perforations around the edges for opening the item.

Multiple sheet

For the best processing, continuously seal all four edges, preferably with no gaps larger than 1 mm.

If you use a continuous glue strip, you must apply it along the entire length of the shorter panel’s top edge. The top and bottom panels must not meet in the middle.

If you’re using a perforated clip seal, test the strength of your perforation by bending it back and forth at least five times. This will ensure your mail item is strong enough to withstand machine processing.