I was recently looking at a map of the Axis occupation of Greece, and I was a bit surprised to notice that Thessaloniki was under German control

Places like Athens (the capital), Crete, and some islands make sense for defense purposes, rather than the less competent Italian army defending them

But Thessaloniki is far from the front and is already defended from Allied attack by Crete, etc. More significantly, Germany's Bulgarian ally had claims to the city - Bulgaria had tried to annex it in past wars, and at the very least claimed the areas outside of the city populated by ethnic Bulgarians. However, Germany didn't grant the city to Bulgaria.

All of this seems odd to me - Thessaloniki seemed to only impose costs on Germany for occupation, while souring their relations with Bulgaria and even Italy. It also seems unusual for Germany during the early part of the war - Odessa was put under Romanian control and Sarajevo under Croatian control, for example

I know Thessaloniki had a large Jewish population, was their extermination Germany's goal? Or could it have something to do with relations with Turkey?