diff --git a/app/src/main/java/eu/faircode/email/ConnectionHelper.java b/app/src/main/java/eu/faircode/email/ConnectionHelper.java
index 4a59ed6a39..08283c8556 100644
--- a/app/src/main/java/eu/faircode/email/ConnectionHelper.java
+++ b/app/src/main/java/eu/faircode/email/ConnectionHelper.java
@@ -210,6 +210,10 @@ public class ConnectionHelper {
     }
 
     private static Boolean isMetered(Context context) {
+        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
+        boolean standalone_vpn = prefs.getBoolean("standalone_vpn", false);
+        boolean require_validated = prefs.getBoolean("require_validated", false);
+
         ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
         if (cm == null) {
             Log.i("isMetered: no connectivity manager");
@@ -248,10 +252,17 @@ public class ConnectionHelper {
 
         Log.i("isMetered: active caps=" + caps);
 
-        if (caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN) &&
-                !caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)) {
-            Log.i("isMetered: no internet");
-            return null;
+        if (caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)) {
+            if (!caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_INTERNET)) {
+                Log.i("isMetered: no internet");
+                return null;
+            }
+            if (require_validated &&
+                    Build.VERSION.SDK_INT >= Build.VERSION_CODES.M &&
+                    !caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)) {
+                Log.i("isMetered: not validated");
+                return null;
+            }
         }
 
         if (!caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_RESTRICTED)) {
@@ -265,8 +276,6 @@ public class ConnectionHelper {
             return null;
         }
 
-        SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(context);
-        boolean standalone_vpn = prefs.getBoolean("standalone_vpn", false);
         if (standalone_vpn ||
                 caps.hasCapability(NetworkCapabilities.NET_CAPABILITY_NOT_VPN)) {
             // NET_CAPABILITY_NOT_METERED is unreliable on older Android versions
diff --git a/app/src/main/java/eu/faircode/email/FragmentOptionsConnection.java b/app/src/main/java/eu/faircode/email/FragmentOptionsConnection.java
index dc2b77a153..69a8fce86d 100644
--- a/app/src/main/java/eu/faircode/email/FragmentOptionsConnection.java
+++ b/app/src/main/java/eu/faircode/email/FragmentOptionsConnection.java
@@ -59,6 +59,7 @@ public class FragmentOptionsConnection extends FragmentBase implements SharedPre
     private Spinner spDownload;
     private SwitchCompat swRoaming;
     private SwitchCompat swRlah;
+    private SwitchCompat swValidated;
     private EditText etTimeout;
     private SwitchCompat swPreferIp4;
     private SwitchCompat swStandaloneVpn;
@@ -71,7 +72,8 @@ public class FragmentOptionsConnection extends FragmentBase implements SharedPre
     private TextView tvNetworkInfo;
 
     private final static String[] RESET_OPTIONS = new String[]{
-            "metered", "download", "roaming", "rlah", "timeout", "prefer_ip4", "standalone_vpn", "tcp_keep_alive", "ssl_harden"
+            "metered", "download", "roaming", "rlah",
+            "require_validated", "timeout", "prefer_ip4", "standalone_vpn", "tcp_keep_alive", "ssl_harden"
     };
 
     @Override
@@ -88,6 +90,7 @@ public class FragmentOptionsConnection extends FragmentBase implements SharedPre
         spDownload = view.findViewById(R.id.spDownload);
         swRoaming = view.findViewById(R.id.swRoaming);
         swRlah = view.findViewById(R.id.swRlah);
+        swValidated = view.findViewById(R.id.swValidated);
         etTimeout = view.findViewById(R.id.etTimeout);
         swPreferIp4 = view.findViewById(R.id.swPreferIp4);
         swStandaloneVpn = view.findViewById(R.id.swStandaloneVpn);
@@ -141,6 +144,14 @@ public class FragmentOptionsConnection extends FragmentBase implements SharedPre
             }
         });
 
+        swValidated.setVisibility(Build.VERSION.SDK_INT < Build.VERSION_CODES.M ? View.GONE : View.VISIBLE);
+        swValidated.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
+                prefs.edit().putBoolean("require_validated", checked).apply();
+            }
+        });
+
         etTimeout.addTextChangedListener(new TextWatcher() {
             @Override
             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
@@ -307,6 +318,8 @@ public class FragmentOptionsConnection extends FragmentBase implements SharedPre
         swRoaming.setChecked(prefs.getBoolean("roaming", true));
         swRlah.setChecked(prefs.getBoolean("rlah", true));
 
+        swValidated.setChecked(prefs.getBoolean("require_validated", false));
+
         int timeout = prefs.getInt("timeout", 0);
         etTimeout.setText(timeout == 0 ? null : Integer.toString(timeout));
         etTimeout.setHint(Integer.toString(EmailService.DEFAULT_CONNECT_TIMEOUT));
diff --git a/app/src/main/res/layout/fragment_options_connection.xml b/app/src/main/res/layout/fragment_options_connection.xml
index ee7b6e52c6..2e040f7a8e 100644
--- a/app/src/main/res/layout/fragment_options_connection.xml
+++ b/app/src/main/res/layout/fragment_options_connection.xml
@@ -163,6 +163,17 @@
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintTop_toBottomOf="@id/tvRlahHint" />
 
+        <androidx.appcompat.widget.SwitchCompat
+            android:id="@+id/swValidated"
+            android:layout_width="0dp"
+            android:layout_height="wrap_content"
+            android:layout_marginTop="12dp"
+            android:text="@string/title_advanced_validated"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@id/tvAdvanced"
+            app:switchPadding="12dp" />
+
         <eu.faircode.email.FixedTextView
             android:id="@+id/tvTimeout"
             android:layout_width="0dp"
@@ -174,7 +185,7 @@
             android:textColor="?android:attr/textColorPrimary"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintStart_toStartOf="parent"
-            app:layout_constraintTop_toBottomOf="@id/tvAdvanced" />
+            app:layout_constraintTop_toBottomOf="@id/swValidated" />
 
         <eu.faircode.email.FixedTextView
             android:id="@+id/tvTimeoutHint"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index b18b474391..5503f2eb4d 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -337,6 +337,7 @@
     <string name="title_advanced_download">Automatically download messages and attachments on a metered connection up to</string>
     <string name="title_advanced_roaming">Download messages and attachments while roaming</string>
     <string name="title_advanced_rlah">Roam like at home</string>
+    <string name="title_advanced_validated">Require a validated (checked) connection</string>
     <string name="title_advanced_timeout">Connection timeout (seconds)</string>
     <string name="title_advanced_prefer_ip4">Prefer IPv4 over IPv6</string>
     <string name="title_advanced_standalone_vpn" translatable="false">Standalone VPN (debug only)</string>