IMAP: logout from the server with a LOGOUT command

CLOSE, which was used previously, only expunges messages and deselects
folder, and it should only be called if some folder is selected. For that,
Imap.close_folder() method is used.

src/imap/mod.rs

@@ -314,9 +314,15 @@ impl Imap {
     }
 
     async fn unsetup_handle(&mut self, context: &Context) {
+        // Close folder if messages should be expunged
+        if let Err(err) = self.close_folder(context).await {
+            warn!(context, "failed to close folder: {:?}", err);
+        }
+
+        // Logout from the server
         if let Some(mut session) = self.session.take() {
-            if let Err(err) = session.close().await {
+            if let Err(err) = session.logout().await {
-                warn!(context, "failed to close connection: {:?}", err);
+                warn!(context, "failed to logout: {:?}", err);
             }
         }
         self.connected = false;

src/imap/select_folder.rs

@@ -27,7 +27,7 @@ impl Imap {
     ///
     /// CLOSE is considerably faster than an EXPUNGE, see
     /// https://tools.ietf.org/html/rfc3501#section-6.4.2
-    async fn close_folder(&mut self, context: &Context) -> Result<()> {
+    pub(super) async fn close_folder(&mut self, context: &Context) -> Result<()> {
         if let Some(ref folder) = self.config.selected_folder {
             info!(context, "Expunge messages in \"{}\".", folder);