diff --git a/app/src/main/java/eu/faircode/email/Core.java b/app/src/main/java/eu/faircode/email/Core.java
index 9c98e35be4..60805224b7 100644
--- a/app/src/main/java/eu/faircode/email/Core.java
+++ b/app/src/main/java/eu/faircode/email/Core.java
@@ -999,7 +999,8 @@ class Core {
             throw new IllegalArgumentException("self");
 
         // De-classify
-        if (MessageClassifier.canClassify(folder.type))
+        if (MessageClassifier.canClassify(folder.type) &&
+                MessageClassifier.canClassify(target.type))
             for (EntityMessage message : messages)
                 MessageClassifier.classify(message, false, context);