diff --git a/internal/protocol/constants.go b/internal/protocol/constants.go
index 09e76a6..28c7e17 100644
--- a/internal/protocol/constants.go
+++ b/internal/protocol/constants.go
@@ -33,4 +33,5 @@ const (
 	MessageUnknownCommand                    = "500 Unknown command"
 	MessageErrorHappened                     = "403 Failed to process command:"
 	MessageListOfNewsgroupsFollows           = "215 list of newsgroups follows"
+	MessageSyntaxError                       = "501 Syntax Error"
 )
diff --git a/internal/server/handler.go b/internal/server/handler.go
index a8448d8..b0af816 100644
--- a/internal/server/handler.go
+++ b/internal/server/handler.go
@@ -22,12 +22,13 @@ func NewHandler(db *sqlx.DB) *Handler {
 		protocol.CommandDate:         h.handleDate,
 		protocol.CommandQuit:         h.handleQuit,
 		protocol.CommandList:         h.handleList,
+		protocol.CommandMode:         h.handleModeReader,
 	}
 	return h
 }
 
 func (h *Handler) handleCapabilities(s *Session, arguments []string) error {
-	return s.tconn.PrintfLine(Capabilities.String())
+	return s.tconn.PrintfLine(s.capabilities.String())
 }
 
 func (h *Handler) handleDate(s *Session, arguments []string) error {
@@ -81,7 +82,7 @@ func (h *Handler) handleList(s *Session, arguments []string) error {
 		}
 	default:
 		{
-			return s.tconn.PrintfLine(protocol.MessageUnknownCommand)
+			return s.tconn.PrintfLine(protocol.MessageSyntaxError)
 		}
 	}
 
@@ -90,6 +91,18 @@ func (h *Handler) handleList(s *Session, arguments []string) error {
 	return s.tconn.PrintfLine(sb.String())
 }
 
+func (h *Handler) handleModeReader(s *Session, arguments []string) error {
+	if len(arguments) == 0 || arguments[0] != "READER" {
+		return s.tconn.PrintfLine(protocol.MessageSyntaxError)
+	}
+
+	(&s.capabilities).Remove(protocol.ModeReaderCapability)
+	(&s.capabilities).Add(protocol.Capability{Type: protocol.ReaderCapability})
+	s.mode = SessionModeReader
+
+	return s.tconn.PrintfLine(protocol.MessageReaderModePostingProhibited) // TODO vary on auth status
+}
+
 func (h *Handler) Handle(s *Session, message string) error {
 	splittedMessage := strings.Split(message, " ")
 	for i, v := range splittedMessage {
diff --git a/internal/server/session.go b/internal/server/session.go
index 1b78d89..ce9b159 100644
--- a/internal/server/session.go
+++ b/internal/server/session.go
@@ -9,6 +9,13 @@ import (
 	"net/textproto"
 )
 
+type SessionMode int
+
+const (
+	SessionModeTransit = iota
+	SessionModeReader
+)
+
 type Session struct {
 	ctx          context.Context
 	capabilities protocol.Capabilities
@@ -17,6 +24,7 @@ type Session struct {
 	id           string
 	closed       chan<- bool
 	h            *Handler
+	mode         SessionMode
 }
 
 func NewSession(ctx context.Context, conn net.Conn, caps protocol.Capabilities, id string, closed chan<- bool, handler *Handler) (*Session, error) {
@@ -37,6 +45,7 @@ func NewSession(ctx context.Context, conn net.Conn, caps protocol.Capabilities,
 		id:           id,
 		closed:       closed,
 		h:            handler,
+		mode:         SessionModeTransit,
 	}
 
 	go s.loop()
@@ -49,7 +58,7 @@ func (s *Session) loop() {
 		close(s.closed)
 	}()
 
-	err := s.tconn.PrintfLine(protocol.MessageReaderModePostingProhibited) // by default access mode is read-only
+	err := s.tconn.PrintfLine(protocol.MessageNNTPServiceReadyPostingProhibited) // by default access mode is read-only
 	if err != nil {
 		s.conn.Close()
 		return