A system for inserting contents in an envelope includes a holder for empty envelopes, a flap opener, conveying elements for conveying the envelope from the holder to a packing pocket where the envelopes are filled, a supply device for supplying the envelope contents to and into the packing pocket, and removal elements for forwarding the filled envelope. The conveying elements include a funnel for orientation of the envelope relative to the packing pocket. The funnel is mobile at a first angle (W1) with respect to a flap guide of the packing pocket. The conveying elements further include a pulling means for pulling the envelope over the packing pocket. The pulling means cooperates temporarily with the flap guide of the packing pocket and is mobile at a second angle (W2) with respect to the flap guide. The conveying elements include means for synchronizing the movement of the funnel and the pulling means.