Realign this front door
If three corners match but the fourth is off like you describe then it means that either the door jamb is not a vertical flat plane of that the door itself is warped. It is most likely to be the door because presumably at one time the installation of the door frame/jamb and the door matched up. 

The most normal fix for a warped door like this is to replace it with a new one. And if you are going into that level of work it is totally a good idea to carefully evaluate if the door jamb should be replaced at the same time. Sometimes a new door will fit and work better with a new jamb because the opening can be cleared out all way to the rough opening framing. Then the new jamb can be properly plumbed, checked for square and shimmed on installation.

If an old door is a particularly unique period piece that you would like to try to preserve it may be that it could be worked on to eliminate warpage. This can be labor intensive and end in no hope for recovery if the wood of the door styles is already twisted. On the other hand an antique door may have come apart in the joints and allow the door parts to move around. In this case it may be possible to strip the whole thing back to bare wood and see if it is possible to re-glue the joints. Sometimes this can also be achieved by attaching surface mounted brass plates on both sides of the door at the bottom or top.