My office front door constantly slams as visitors don’t close it by hand, they just leave it to swing back. Do you have anything that can make the door close softly but not delay the closing too much as people come in quickly and don’t check whether it’s closed behind them and I’m concerned about security but can’t stand the constant noise and damage to the door. Can you suggest a solution?

A hydraulic overhead door closer with adjustable closing speed and adjustable latching action will solve your problem.  You can set the closing speed to fast, then use the latching action to give a slower firm close at the last 10° or so.  Which door closer you go for depends on all the normal considerations; door timber or uPVC, width of door, push or pull side, budget? etc.  A good place to start looking is the excellent Geze TS4000, which will be able to handle almost any situation, then you can look at the lower spec models depending on the considerations listed.