Can you examine goods before paying courier in Poland?

Basically, my father-in-law ordered something and it came by a courier you have to pay. What he got is not what he ordered.
Now I am thinking of purchasing something which will cost close to 300zl and I don't want to get ripped off. So am I able to open the package and check to make sure the goods are correct before I pay the courier or not?

Of course - it is always recommended - in case if something gets wrong. But opening the original Item box may not be welcomed by the seller in case of a return. Polish law however allows to return Items purchased online (even opened - in working order) up to 10 days after buy - without providing any reason.

Thanks for the information, much appreciated.

Looker is right. Courier may not want to wait for you opening the package, but he has to, as in case of damage you need his written statement that the damage was caused during transport. I am not sure weather you can open package before paying to courier.