Yugoslavia, which wasn't a Warsaw Pact member, allowed hundreds of thousands of its citizens to work temporarily in Western Europe -- mainly Germany -- beginning in the 1960s. I also want to add that while it was indeed generally hard to emigrate from the Soviet bloc, exceptions were often made for members of ethnic minorities. Many Polish Jews were more or less driven out during an antisemitic campaign after the Six Day War, and West Germany paid Romania to allow the the emigration of German Romanians during the 1980s, for example. The payment was supposed to be reimbursement for the emigres' education, which illustrates what these regimes claimed was the purpose of the emigration restrictions -- the state had invested in these people, and they should be able to collect on their investment.