I am planning to check-in my luggage 4 hrs before an international flight. Once I check-in my luggage and receive the boarding pass, can I leave the airport and come back after 1.5 hrs? I have an Indian passport.
Just dropped my Mum at Mumbai airport this morning and there are security guards outside the check-in hall. They were checking tickets and id of passengers entering. That being said, one of them tried to prevent 2 people leaving, but they said they were signed out and another guard motioned to let them through. So it was OK and if you can drop your bag off that early, should be able to get out again.
Also, there was some kind of government visitor last night (17th), so security might relax a bit after they've left. Edit: ignore this, sounds like the security was normal from comments above.
The main problem is going to be getting away from and back to the airport in 2-3 hours. It's not exactly well connected. You'd be able to make Andheri, or Ghatkopar on the metro, but I can't imagine what you'd actually want to do around there (a 2 wheeler would open up more options).
In most airports check-in area is not a secured area and you can enter it and leave it as you wish, no matter whether you have a boarding pass or luggage or whether you plan to fly or not. It's just a big hall behind the entrance doors.
So if Mumbai airport doesn't have some peculiar plan, you can leave it and come back later at any time.
I have done this several times! Whenever I had a connecting flight halt more than a 4hr, I went out to buy stuff or eat something. So the answer to your question is
YES, they do allow
If you are holding valid ticket(When I say valid, it means your flight is scheduled and not departed yet) of any flight, you are good to go out and come in any number of times at any Airports in India. You valid ticket and identity proof are two things security will check.
Hope this helps!