Tools > Mail Server > Specific IP
So, after i checked 16 IP Addresses for Blackmails, i found 4, that aren't listed in public Blackmails.
I added these 4 to my Server where Plesk is running, and tested it (again and again, with these IP Addresses.)
First: Spam in Gmail, Spam in Yahoo, Spam in Hotmail (Atleast it hotmail received it in some way, yay)
Second: Spam in Gmail, Spam in Yahoo, Hotmail didnt received it, with the same message, that my network is on their Blocklist.
Third: Spam in Gmail, Spam in Yahoo, Spam in Hotmail (atleast it received)
fourth: No Spam in Gmail, Spam in Yahoo, Spam in Hotmail. But its a little win, because now i know, its definitely my IP Address. I will contact my Datacenter and i will ask, if they can change some IP Addresses, because they are Blacklisted. Maybe i get some new to test it with.
Thanks for everyones Help, without you, i would be here without the knowledge for the reason of my Problem.
I will write again, when everything works.
Thanks to all, and Sorry for everyone who had to read my shitty english