use io package from writing csv

email_client.py

@@ -1,6 +1,7 @@
 #!/usr/bin/env python3
 
 import sys
+import io
 import imaplib
 import os
 import email
@@ -177,10 +178,12 @@ class Participation(object):
                   self.registration_date.isoformat(), self._role, str(self.fee), str(self.farewell_event),
                   str(self.gwinner_award), str(self.labtour), str(self._food_vegi), str(self._food_vegan),
                   str(self._food_gluten), str(self._food_normal)]
-        with open(filename, "w") as f:
-            f.write("; ".join(header))
-            f.write("\n")
-            f.write("; ".join(values))
+
+        with io.open(filename, mode="w", encoding="UTF8") as fd:
+            fd.write("; ".join(header))
+            fd.write("\n")
+            fd.write("; ".join(values))
+        
         return filename
 
     def __str__(self):