diff --git a/app/src/main/java/eu/faircode/email/ApplicationEx.java b/app/src/main/java/eu/faircode/email/ApplicationEx.java
index 177b27e8a0..93b0ed071b 100644
--- a/app/src/main/java/eu/faircode/email/ApplicationEx.java
+++ b/app/src/main/java/eu/faircode/email/ApplicationEx.java
@@ -581,7 +581,8 @@ public class ApplicationEx extends Application
             boolean reply_all = prefs.getBoolean("reply_all", false);
             if (reply_all)
                 editor.remove("reply_all").putString("answer_action", "reply_all");
-        }
+        } else if (version < 1841)
+            ContactInfo.clearCache(context);
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O && !BuildConfig.DEBUG)
             editor.remove("background_service");
diff --git a/app/src/main/java/eu/faircode/email/ContactInfo.java b/app/src/main/java/eu/faircode/email/ContactInfo.java
index ab6d6cf581..502452eace 100644
--- a/app/src/main/java/eu/faircode/email/ContactInfo.java
+++ b/app/src/main/java/eu/faircode/email/ContactInfo.java
@@ -115,6 +115,7 @@ public class ContactInfo {
     private static final int FAVICON_READ_TIMEOUT = 10 * 1000; // milliseconds
     private static final long CACHE_CONTACT_DURATION = 2 * 60 * 1000L; // milliseconds
     private static final long CACHE_FAVICON_DURATION = 2 * 7 * 24 * 60 * 60 * 1000L; // milliseconds
+    private static final float MIN_FAVICON_LUMINANCE = 0.2f;
 
     // https://css-tricks.com/prefetching-preloading-prebrowsing/
     // https://developer.mozilla.org/en-US/docs/Web/Performance/dns-prefetch
@@ -447,6 +448,19 @@ public class ContactInfo {
                             try {
                                 Favicon favicon = future.get();
                                 if (favicon != null) {
+                                    float lum = ImageHelper.getLuminance(favicon.bitmap);
+                                    if (lum < MIN_FAVICON_LUMINANCE) {
+                                        Bitmap bitmap = Bitmap.createBitmap(
+                                                favicon.bitmap.getWidth(),
+                                                favicon.bitmap.getHeight(),
+                                                favicon.bitmap.getConfig());
+                                        bitmap.eraseColor(Color.WHITE);
+                                        Canvas canvas = new Canvas(bitmap);
+                                        canvas.drawBitmap(favicon.bitmap, 0, 0, null);
+                                        favicon.bitmap.recycle();
+                                        favicon.bitmap = bitmap;
+                                    }
+
                                     info.bitmap = favicon.bitmap;
                                     info.type = favicon.type;
                                     info.verified = favicon.verified;
@@ -777,14 +791,7 @@ public class ContactInfo {
             Bitmap bitmap = ImageHelper.getScaledBitmap(connection.getInputStream(), url.toString(), mimeType, scaleToPixels);
             if (bitmap == null)
                 throw new FileNotFoundException("decodeStream");
-            else {
-                Bitmap favicon = Bitmap.createBitmap(bitmap.getWidth(), bitmap.getHeight(), bitmap.getConfig());
-                favicon.eraseColor(Color.WHITE);
-                Canvas canvas = new Canvas(favicon);
-                canvas.drawBitmap(bitmap, 0, 0, null);
-                bitmap.recycle();
-                return new Favicon(favicon);
-            }
+            return new Favicon(bitmap);
         } finally {
             connection.disconnect();
         }
diff --git a/app/src/main/java/eu/faircode/email/FragmentDialogTheme.java b/app/src/main/java/eu/faircode/email/FragmentDialogTheme.java
index 5308046bc5..c0bdbf0c3c 100644
--- a/app/src/main/java/eu/faircode/email/FragmentDialogTheme.java
+++ b/app/src/main/java/eu/faircode/email/FragmentDialogTheme.java
@@ -254,8 +254,6 @@ public class FragmentDialogTheme extends FragmentDialogBase {
                     public void onClick(DialogInterface dialog, int which) {
                         getActivity().getIntent().putExtra("tab", "display");
 
-                        ContactInfo.clearCache(context);
-
                         int optionId = rgThemeOptions.getCheckedRadioButtonId();
                         boolean reverse = (swReverse.isEnabled() && swReverse.isChecked());
                         boolean dark = (rgThemeOptions.isEnabled() && optionId == R.id.rbThemeDark);
diff --git a/app/src/main/java/eu/faircode/email/ImageHelper.java b/app/src/main/java/eu/faircode/email/ImageHelper.java
index 703d67d5fb..3fc4c22f04 100644
--- a/app/src/main/java/eu/faircode/email/ImageHelper.java
+++ b/app/src/main/java/eu/faircode/email/ImageHelper.java
@@ -912,6 +912,23 @@ class ImageHelper {
         }
     }
 
+    static float getLuminance(Bitmap bitmap) {
+        int n = 0;
+        float lum = 0;
+        int w = bitmap.getWidth();
+        int h = bitmap.getHeight();
+        for (int y = 0; y < h; y++)
+            for (int x = 0; x < w; x++) {
+                int color = bitmap.getPixel(x, y);
+                if (color != Color.TRANSPARENT) {
+                    n++;
+                    lum += ColorUtils.calculateLuminance(color);
+                }
+            }
+
+        return (lum / n);
+    }
+
     static class AnnotatedSource {
         private String source;
         private int width = 0;