diff --git a/app/src/main/java/eu/faircode/email/FragmentOptionsMisc.java b/app/src/main/java/eu/faircode/email/FragmentOptionsMisc.java
index 8ecd76539c..bb5867e316 100644
--- a/app/src/main/java/eu/faircode/email/FragmentOptionsMisc.java
+++ b/app/src/main/java/eu/faircode/email/FragmentOptionsMisc.java
@@ -234,6 +234,7 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
     private EditText etNativeArcWhitelist;
     private SwitchCompat swInfra;
     private SwitchCompat swDupMsgId;
+    private SwitchCompat swThreadByRef;
     private EditText etKeywords;
     private SwitchCompat swTestIab;
     private Button btnImportProviders;
@@ -296,7 +297,7 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
             "max_backoff_power", "logarithmic_backoff",
             "exact_alarms",
             "native_dkim", "native_arc", "native_arc_whitelist",
-            "infra", "dup_msgids", "global_keywords", "test_iab"
+            "infra", "dup_msgids", "thread_byref", "global_keywords", "test_iab"
     };
 
     private final static String[] RESET_QUESTIONS = new String[]{
@@ -478,6 +479,7 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
         etNativeArcWhitelist = view.findViewById(R.id.etNativeArcWhitelist);
         swInfra = view.findViewById(R.id.swInfra);
         swDupMsgId = view.findViewById(R.id.swDupMsgId);
+        swThreadByRef = view.findViewById(R.id.swThreadByRef);
         etKeywords = view.findViewById(R.id.etKeywords);
         swTestIab = view.findViewById(R.id.swTestIab);
         btnImportProviders = view.findViewById(R.id.btnImportProviders);
@@ -1773,6 +1775,13 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
             }
         });
 
+        swThreadByRef.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
+                prefs.edit().putBoolean("thread_byref", checked).apply();
+            }
+        });
+
         etKeywords.addTextChangedListener(new TextWatcher() {
             @Override
             public void beforeTextChanged(CharSequence s, int start, int count, int after) {
@@ -2509,6 +2518,7 @@ public class FragmentOptionsMisc extends FragmentBase implements SharedPreferenc
             etNativeArcWhitelist.setText(prefs.getString("native_arc_whitelist", null));
             swInfra.setChecked(prefs.getBoolean("infra", false));
             swDupMsgId.setChecked(prefs.getBoolean("dup_msgids", false));
+            swThreadByRef.setChecked(prefs.getBoolean("thread_byref", true));
             etKeywords.setText(prefs.getString("global_keywords", null));
             swTestIab.setChecked(prefs.getBoolean("test_iab", false));
 
diff --git a/app/src/main/java/eu/faircode/email/MessageHelper.java b/app/src/main/java/eu/faircode/email/MessageHelper.java
index f71fb9a734..5bed67489f 100644
--- a/app/src/main/java/eu/faircode/email/MessageHelper.java
+++ b/app/src/main/java/eu/faircode/email/MessageHelper.java
@@ -1872,7 +1872,8 @@ public class MessageHelper {
         }
 
         // Common reference
-        if (thread == null && refs.size() > 0) {
+        boolean thread_byref = prefs.getBoolean("thread_byref", true);
+        if (thread == null && refs.size() > 0 && thread_byref) {
             String ref = refs.get(0);
             if (!Objects.equals(ref, msgid))
                 thread = account + ":" + ref;
diff --git a/app/src/main/res/layout/fragment_options_misc.xml b/app/src/main/res/layout/fragment_options_misc.xml
index 70039093ab..747692c4cb 100644
--- a/app/src/main/res/layout/fragment_options_misc.xml
+++ b/app/src/main/res/layout/fragment_options_misc.xml
@@ -2206,6 +2206,17 @@
                     app:layout_constraintTop_toBottomOf="@id/tvDkimVerifyHint"
                     app:switchPadding="12dp" />
 
+                <androidx.appcompat.widget.SwitchCompat
+                    android:id="@+id/swThreadByRef"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:layout_marginTop="12dp"
+                    android:text="@string/title_advanced_thread_by_ref"
+                    app:layout_constraintEnd_toEndOf="parent"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toBottomOf="@id/swDupMsgId"
+                    app:switchPadding="12dp" />
+
                 <EditText
                     android:id="@+id/etKeywords"
                     android:layout_width="0dp"
@@ -2216,7 +2227,7 @@
                     android:textAppearance="@style/TextAppearance.AppCompat.Small"
                     app:layout_constraintEnd_toEndOf="parent"
                     app:layout_constraintStart_toStartOf="parent"
-                    app:layout_constraintTop_toBottomOf="@id/swDupMsgId" />
+                    app:layout_constraintTop_toBottomOf="@id/swThreadByRef" />
 
                 <TextView
                     android:id="@+id/tvKeywordsHint"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 7a3e8f203c..2a9b2c2baa 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -881,6 +881,7 @@
     <string name="title_advanced_native_arc" translatable="false">Native ARC verification</string>
     <string name="title_advanced_infra" translatable="false">Show infrastructure</string>
     <string name="title_advanced_dup_msgid" translatable="false">Duplicates by message ID</string>
+    <string name="title_advanced_thread_by_ref" translatable="false">Thread by common reference</string>
     <string name="title_advanced_global_keywords" translatable="false">Global keywords</string>
     <string name="title_advanced_test_iab" translatable="false">Test IAB</string>
     <string name="title_advanced_import_providers" translatable="false">Import providers</string>