Fixed back from activities

app/src/main/java/eu/faircode/email/ActivityDmarc.java

@@ -33,6 +33,7 @@ import android.text.style.StyleSpan;
 import android.text.style.TypefaceSpan;
 import android.util.Pair;
 import android.view.LayoutInflater;
+import android.view.MenuItem;
 import android.view.View;
 import android.widget.TextView;
 
@@ -86,6 +87,16 @@ public class ActivityDmarc extends ActivityBase {
         load();
     }
 
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        int itemId = item.getItemId();
+        if (itemId == android.R.id.home) {
+            finish();
+            return true;
+        }
+        return super.onOptionsItemSelected(item);
+    }
+
     private void load() {
         Intent intent = getIntent();
         Uri uri = intent.getData();