Thanks for the feedback!
The delivery mission is intentionally locked to not ruin sequence for your save file in the next update (it's planned to be relatively huge). I forgot to add message in the game to inform about that.
Thanks for letting me know about the mission being unavailable, I'll go try the others. I really liked the game concept and the gameplay itself; it's nice and calm, yet interesting.
While flying, I noticed a lot of ships in the distance. It would be cool if they added some events involving them in future updates (just a suggestion that I think sounds pretty good)