Updated FAQ

FAQ.md

@@ -126,6 +126,7 @@ See [here](https://support.microsoft.com/en-us/help/12409/microsoft-account-app-
 * Encryption: there is too little interest in sending/receiving encrypted messages to justify putting effort into this.
 * Multiple select: swiping is easier and doesn't have the risk of accidental touches, so multiple select would not add anything.
 * Swipe left/right for previous/next message: this would be confusing since sometimes a message and sometimes a message conversation would be shown.
+* Preview message text: this is not always possible because the message text is initially not downloaded for large messages and besides that the subject is supposed to tell what the message is about.
 
 <a name="FAQ16"></a>
 **(16) Why are messages not being synchronized?**