diff --git a/go.mod b/go.mod
index 9b604df..bc80f97 100644
--- a/go.mod
+++ b/go.mod
@@ -4,13 +4,11 @@ go 1.17
 
 require (
 	github.com/BurntSushi/toml v1.0.0
+	github.com/dlclark/regexp2 v1.4.0
 	github.com/google/uuid v1.3.0
 	github.com/jmoiron/sqlx v1.3.4
 	github.com/mattn/go-sqlite3 v1.14.10
 	github.com/pressly/goose/v3 v3.5.0
 )
 
-require (
-	github.com/dlclark/regexp2 v1.4.0 // indirect
-	github.com/pkg/errors v0.9.1 // indirect
-)
+require github.com/pkg/errors v0.9.1 // indirect
diff --git a/internal/models/article.go b/internal/models/article.go
index 39e04e4..3acdc1f 100644
--- a/internal/models/article.go
+++ b/internal/models/article.go
@@ -14,68 +14,3 @@ type Article struct {
 	Body      string               `db:"body"`
 	Thread    sql.NullString       `db:"thread"`
 }
-
-//func ParseArticle(lines []string) (Article, error) {
-//	article := Article{}
-//	headerBlock := true
-//	for _, v := range lines {
-//		if v == "" {
-//			headerBlock = false
-//		}
-//
-//		if headerBlock {
-//			kv := strings.Split(v, ":")
-//			if len(kv) < 2 {
-//				return Article{}, fmt.Errorf("invalid header format")
-//			}
-//
-//			kv[0] = strings.TrimSpace(kv[0])
-//			kv[1] = strings.TrimSpace(kv[1])
-//
-//			if !protocol.IsMessageHeaderAllowed(kv[0]) {
-//				return Article{}, fmt.Errorf("invalid header element")
-//			}
-//			if kv[1] == "" {
-//				return Article{}, fmt.Errorf("header value should not be empty")
-//			}
-//
-//			switch kv[0] {
-//			case "Archive":
-//				{
-//					if kv[1] == "yes" {
-//						article.Archive = true
-//					} else {
-//						article.Archive = false
-//					}
-//				}
-//			case "Injection-Date":
-//				{
-//					date, err := mail.ParseDate(kv[1])
-//					if err != nil {
-//						return Article{}, err
-//					}
-//					article.InjectionDate = date
-//				}
-//			case "Date":
-//				{
-//					date, err := mail.ParseDate(kv[1])
-//					if err != nil {
-//						return Article{}, err
-//					}
-//					article.Date = date
-//				}
-//			case "Expires":
-//				{
-//					date, err := mail.ParseDate(kv[1])
-//					if err != nil {
-//						return Article{}, err
-//					}
-//					article.Expires = date
-//				}
-//			}
-//
-//		} else {
-//		}
-//	}
-//	return article, nil
-//}
diff --git a/internal/protocol/constants.go b/internal/protocol/constants.go
index 3e0fcfe..86d9ea5 100644
--- a/internal/protocol/constants.go
+++ b/internal/protocol/constants.go
@@ -70,14 +70,3 @@ const (
 	CapabilityNameImplementation = "IMPLEMENTATION"
 	CapabilityNameModeReader     = "MODE-READER"
 )
-
-const (
-	MessageNNTPServiceReadyPostingProhibited = "201 YANS NNTP Service Ready, posting prohibited"
-	MessageReaderModePostingProhibited       = "201 Reader mode, posting prohibited"
-	MessageNNTPServiceExitsNormally          = "205 NNTP Service exits normally, bye!"
-	MessageErrorHappened                     = "403 Failed to process command:"
-	MessageListOfNewsgroupsFollows           = "215 list of newsgroups follows"
-	MessageNoSuchGroup                       = "411 No such newsgroup"
-	MessageInputArticle                      = "340 Input article; end with <CR-LF>.<CR-LF>"
-	MessageArticleReceived                   = "240 Article received OK"
-)
diff --git a/internal/server/handler.go b/internal/server/handler.go
index 92c51d0..fb30de6 100644
--- a/internal/server/handler.go
+++ b/internal/server/handler.go
@@ -49,11 +49,11 @@ func (h *Handler) handleCapabilities(s *Session, arguments []string, id uint) er
 func (h *Handler) handleDate(s *Session, arguments []string, id uint) error {
 	s.tconn.StartResponse(id)
 	defer s.tconn.EndResponse(id)
-	return s.tconn.PrintfLine("111 %s", time.Now().UTC().Format("20060102150405"))
+	return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 111, Message: time.Now().UTC().Format("20060102150405")}.String())
 }
 
 func (h *Handler) handleQuit(s *Session, arguments []string, id uint) error {
-	s.tconn.PrintfLine(protocol.MessageNNTPServiceExitsNormally)
+	s.tconn.PrintfLine(protocol.NNTPResponse{Code: 205, Message: "NNTP Service exits normally, bye!"}.String())
 	s.conn.Close()
 	return nil
 }
@@ -85,7 +85,7 @@ func (h *Handler) handleList(s *Session, arguments []string, id uint) error {
 			if err != nil {
 				return err
 			}
-			sb.Write([]byte(protocol.MessageListOfNewsgroupsFollows + protocol.CRLF))
+			sb.Write([]byte(protocol.NNTPResponse{Code: 215, Message: "list of newsgroups follows"}.String() + protocol.CRLF))
 			for _, v := range groups {
 				// TODO set actual post permission status
 				c, err := h.backend.GetArticlesCount(&v)
@@ -120,7 +120,7 @@ func (h *Handler) handleList(s *Session, arguments []string, id uint) error {
 				return err
 			}
 
-			sb.Write([]byte(protocol.MessageListOfNewsgroupsFollows + protocol.CRLF))
+			sb.Write([]byte(protocol.NNTPResponse{Code: 215, Message: "list of newsgroups follows"}.String() + protocol.CRLF))
 			for _, v := range groups {
 				desc := ""
 				if v.Description == nil {
@@ -156,7 +156,7 @@ func (h *Handler) handleModeReader(s *Session, arguments []string, id uint) erro
 	(&s.capabilities).Add(protocol.Capability{Type: protocol.ListCapability, Params: "ACTIVE NEWSGROUPS"})
 	s.mode = SessionModeReader
 
-	return s.tconn.PrintfLine(protocol.MessageReaderModePostingProhibited) // TODO vary on auth status
+	return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 201, Message: "Reader mode, posting prohibited"}.String()) // TODO vary on auth status
 }
 
 func (h *Handler) handleGroup(s *Session, arguments []string, id uint) error {
@@ -170,7 +170,7 @@ func (h *Handler) handleGroup(s *Session, arguments []string, id uint) error {
 	g, err := h.backend.GetGroup(arguments[0])
 	if err != nil {
 		if err == sql.ErrNoRows {
-			return s.tconn.PrintfLine(protocol.MessageNoSuchGroup)
+			return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 411, Message: "No such newsgroup"}.String())
 		} else {
 			return err
 		}
@@ -266,7 +266,7 @@ func (h *Handler) handlePost(s *Session, arguments []string, id uint) error {
 		return s.tconn.PrintfLine(protocol.ErrSyntaxError.String())
 	}
 
-	if err := s.tconn.PrintfLine(protocol.MessageInputArticle); err != nil {
+	if err := s.tconn.PrintfLine(protocol.NNTPResponse{Code: 340, Message: "Input article; end with <CR-LF>.<CR-LF>"}.String()); err != nil {
 		return err
 	}
 
@@ -324,7 +324,7 @@ func (h *Handler) handlePost(s *Session, arguments []string, id uint) error {
 		return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 441, Message: err.Error()}.String())
 	}
 
-	return s.tconn.PrintfLine(protocol.MessageArticleReceived)
+	return s.tconn.PrintfLine(protocol.NNTPResponse{Code: 240, Message: "Article received OK"}.String())
 }
 
 func (h *Handler) handleListgroup(s *Session, arguments []string, id uint) error {
diff --git a/internal/server/session.go b/internal/server/session.go
index 8a2dcb5..73213d5 100644
--- a/internal/server/session.go
+++ b/internal/server/session.go
@@ -2,6 +2,7 @@ package server
 
 import (
 	"context"
+	"fmt"
 	"github.com/ChronosX88/yans/internal/models"
 	"github.com/ChronosX88/yans/internal/protocol"
 	"io"
@@ -61,7 +62,7 @@ func (s *Session) loop() {
 		close(s.closed)
 	}()
 
-	err := s.tconn.PrintfLine(protocol.MessageNNTPServiceReadyPostingProhibited) // by default access mode is read-only
+	err := s.tconn.PrintfLine(protocol.NNTPResponse{Code: 201, Message: "YANS NNTP Service Ready, posting prohibited"}.String()) // by default access mode is read-only
 	if err != nil {
 		s.conn.Close()
 		return
@@ -90,7 +91,7 @@ func (s *Session) loop() {
 				err = s.h.Handle(s, message, id)
 				if err != nil {
 					log.Print(err)
-					s.tconn.PrintfLine("%s %s", protocol.MessageErrorHappened, err.Error())
+					s.tconn.PrintfLine(protocol.NNTPResponse{Code: 403, Message: fmt.Sprintf("Failed to process command: %s", err.Error())}.String())
 					s.conn.Close()
 					return
 				}