Stability

During the mechanical sorting process, mailed items are fed into a compartment. Items which are too thin or lack sufficient rigidity will suffer crumpling in the event of collisions.

This often results in damage to items and malfunctioning of sorting equipment.

The same risk applies if an unnecessarily large envelope is used.

Tip:

Ensure that none of the contents of the envelope can shift position by more than around 1 cm.

Items will normally have the necessary rigidity if they reach or exceed the following minimum weights:

To be suitable for machine processing large letters up to B4 format need to have a minimum thickness of 0.5 mm.