A sealed package is a variant of a package that has a proof of authorship and integrity.
Seal impression and name of the sealer is shown in the item's tooltip.
Can be mailed.

Sealed Package tooltip

Obtaining

Sealed Package can be obtained by sealing a package with a seal stamp.

Usage

Seal can be removed by holding the use button until a "seal ripping" animation is finished.
Removing the seal clears the authorship information and returns the item back to a regular package.