Well, many didn't want to admit it for long, but antisemitism wasn't specific only to Germany. Anti-Jewish resentment was felt in a lot of European countries.The rejection of taking in Jewish refugees has an antisemitic edge to it.

Another point was that these refugees were pretty impoverished. To be let out of Germany you had to leave everything of value behind and it was confiscated by the authorities. So Jewish refugees were poor and disliked on antisemitic resentment by a lot of people. Not a good combination.

Also, with the start of the war in 1939, borders were closed to everyone. Leaving Germany and going somewhere else wasn't possible. This is also discussed as one reason that escalated the German antisemitism which later lead to the Holocaust. With the option to remove the jews by emigration, they were forced into closed of ghettos, isolated by the non-jewish population.

That is also part why a lot of people went to colonized places where access wasn't as well controlled. Palestine had Zionist groups helping to circumvent British restrictions of Jewish immigration. Shanghai was another place where a lot of Jews went, you didn't need a visa to go to Shanghai, and there were no restrictions, but as you can imagine, traveling as someone who has nothing around the world to a place where you know no one and don't speak the language isn't easy. Still 18.000 Jews went to Shanghai.