School: Ehrenfried-Walther-von-Tschirnhaus-Gymnasium Dresden
E-Mail-Suffix: ewvt.lernsax.de

Proof that this school use this mail provider:
On the page lernsax.de is on the left side a botton with the text "LernSax Kennenlernen" it means get to know lernsax. You have to click this button.
On this new page is on the left side a botton with the text "Karte der LernSax-Nutzer" it shows you a map of the lernsax users. 
On this map you have to click this circle (https://prnt.sc/1ak5py1).
You can also check the official Website (https://ewvt.de) and the part explaining Lernsax (https://ewvt.de/index.php/kontakt-und-service/lernsax2).
Click the "Impressium" (inprint) botton to check if the school website is ewvt.de