Polish Eastern neighbour can be reached by rail. For example, from Warsaw to Minsk you can get by a direct train between Warsaw-Minsk. This train operates daily and it offers the shipping service. The cheapest alternative is a combination of a commuter train in Brzesc. In turn, from the Warsaw Central to Moscow (Moskva Belorusskaja) one can get by a direct fast train in 18 hours and 15 minutes. The train leaves daily at 15.30.
It should be born in mind that the change to the chassis takes place at the Polish eastern border. It takes about 2 hours. There is so called European tracks spacing in Poland, and since the railway lines in the countries of the former Soviet Union (USSR) have a wider wheelbase, it is necessary to change the wheels at the border which prolongs the journey.
Coming to Poland from Russia or Ukraine, you can check timetables on rasp.yandex.ru Travelling with from Belarus at rw.by, and Moldova at railway.md.
