Yes, the striker is adjustable. Just loosen up the big screws and tap the striker with a hammer to move it and retighten the screws.
If this happens to be a samurai, check the body where the rubber door strap attaches. A lot of times the body lip gets bent out a little bit, from the door being opened too "hard" (either by the wind catching it, or someone just "winging" the door open) and it will bend the lip behind the door strap (you can easily see it, if this is the case). If it is bent, you can take a board and hammer and bend it back in, to keep the door from hitting on it so hard, and the door will close much easier then.