How were German Jewish veterans of WWI treated better by the Nazis?

I've heard several times that German Jewish veterans of World War One were treated less harshly by the Nazi regime...in what way? I've heard, for example, that they were sent to a special camp and not required to do slave labor, or be put to death (obviously), but I've never any further details (such as the name of the camp, although I read once it was Mauthausen, but Wikipedia's entry for that camp doesn't mention it).