Updated FAQ

FAQ.md

@@ -2856,6 +2856,14 @@ The error *User is authenticated but not connected* might occur if:
 * An alias email address is being used as username instead of the primary email address
 * An incorrect login scheme is being used for a shared mailbox: the right scheme is *username@domain\SharedMailboxAlias*
 
+The shared mailbox alias will mostly be the email address of the shared account, like this:
+
+```
+you@example.com\shared@example.com
+```
+
+Note that it should be a backslash and not a forward slash.
+
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