But at the opposite, I don,t want to release it for people abusing of it. Like user saying: "hey, if I send the package with verification process then I'll win" and taking advantage of it.
You are handling other people's money. They are supposed to 100% understand *precisely* what procedures you will follow in all cases, and they should agree to them when they agree to use you as an escrow service. I've never heard of an escrow service with secret rules. Any scheme that leaves you discretion in what to do with other people's money is, IMO, broken. The rules should be 100% precise and clear.
Following the rules to get the result the rules entitle you to is how rules are supposed to work. It's not "taking advantage" of them.
For example, here are some very simple escrow rules:
1) The parties to the escrow agree on the amount to be escrowed and who will deposit the money. The escrow fee is taken from the deposit amount.
2) The parties to the escrow specify what courts or arbitration agencies they will use for disputes.
3) The escrow agency will release funds only on approval of both parties, upon order of a court or arbitration agency they specified in step 2, upon order from a court with jurisdiction over the escrow agency, or upon special, easily objectively-verified release conditions agreed upon by the parties. (For example, one special release condition could be if a particular party fails to present the escrow agency with proof of a particular document by a particular date, the other party gets the escrow amount.)
4) The escrow agency assumes liability only for failure to follow its own rules.
You can, if you wish, also offer your own arbitration service and permit parties to select it in step 2. But if you do this, you should practice 100% separation between the escrow and arbitration services. You can do arbitration by email.