When this option is enabled, the message/ file will not only be encrypted with the receiver's public key, but also with your key. This will enable you to decrypt the message/ file at a later time. This is generally a good idea.
As dizze opsje ynskeakele is sil it berjocht/ de triem net allinnich fersifere wurde mei de publike kaai fan de ûntfanger, mar ek mei jo eigen kaai. Jo kinne dan op in letter momint it berjocht/ de triem ûntsiferje. Dit is oer it generaal in goed idee.