Updated FAQ

FAQ.md

@@ -3411,6 +3411,8 @@ Synchronization for subscribed folders can therefore be disable, saving folder c
 <a name="faq163"></a>
 **(163) What is message classification?**
 
+**This is an experimental feature**
+
 Message classification will attempt to automatically group emails into classes, based on their contents,
 using [Bayesian statistics](https://en.wikipedia.org/wiki/Bayesian_statistics).
 In the context of FairEmail, a folder is a class.
@@ -3432,6 +3434,8 @@ Moving a message from another email client will not result in reclassification b
 
 Classification is optimized to use as little resources as possible, but will inevitably use some extra battery power.
 
+You can delete all classification data by turning classification three times off.
+
 Automatic message classification is a pro feature, except for the spam folder.
 
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