diff --git a/.gitignore b/.gitignore
index 332ba63..534271a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,4 @@
-mailsrv
+builds
+outbox
+
+*.ini
diff --git a/Makefile b/Makefile
index b8626c2..9c85ebc 100644
--- a/Makefile
+++ b/Makefile
@@ -1,26 +1,20 @@
 .DEFAULT_GOAL := build
 
-fmt:
+.DEFAULT_GOAL := run
+
+BIN_NAME := mailsrv
+ROOT_DIR := $(dir $(realpath $(lastword $(MAKEFILE_LIST))))
+BUILD_DIR := $(ROOT_DIR)builds
+
+build: format lint
+	@mkdir -p $(BUILD_DIR)
+	@go build -o $(BUILD_DIR)/$(BIN_NAME) main.go
+
+format:
 	go fmt ./...
-.PHONY:fmt
 
-lint: fmt
-	golint ./...
-.PHONY:lint
-
-vet: fmt
-	go vet ./...
-	shadow ./...
-.PHONY:vet
-
-build:
-	go build -o mailsrv
-.PHONY:build
-
-build-check: vet
-	go build -o mailsrv
-.PHONY:build
+lint:
+	golangci-lint run --fix
 
 test:
 	go test ./...
-.PHONY:test
diff --git a/go.mod b/go.mod
index ad11d7b..b374ca0 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,6 @@
 module mailsrv
 
-go 1.17
+go 1.20
 
 require (
 	github.com/alecthomas/kingpin/v2 v2.3.2
diff --git a/go.sum b/go.sum
index ae9e8cb..93116ed 100644
--- a/go.sum
+++ b/go.sum
@@ -5,7 +5,6 @@ github.com/alecthomas/units v0.0.0-20211218093645-b94a6e3cc137/go.mod h1:OMCwj8V
 github.com/coreos/go-systemd/v22 v22.5.0/go.mod h1:Y58oyj3AT4RCenI/lSvhwexgC+NSVTIJ3seZv2GcEnc=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
-github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/mattn/go-colorable v0.1.12 h1:jF+Du6AlPIjs2BiUiQlKOX0rt3SujHxPnksPKZbaA40=
 github.com/mattn/go-colorable v0.1.12/go.mod h1:u5H1YNBxpqRaxsYJYSkiCWKzEfiAb1Gb520KVy5xxl4=
@@ -18,13 +17,8 @@ github.com/rs/xid v1.4.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
 github.com/rs/zerolog v1.29.1 h1:cO+d60CHkknCbvzEWxP0S9K6KqyTjrCNUy1LdQLCGPc=
 github.com/rs/zerolog v1.29.1/go.mod h1:Le6ESbR7hc+DP6Lt1THiV8CQSdkkNrd3R0XbEgp3ZBU=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
-github.com/stretchr/objx v0.4.0/go.mod h1:YvHI0jy2hoMjB+UWwv71VJQ9isScKT/TqJzVSSt89Yw=
-github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
-github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
-github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.2 h1:+h33VjcLVPDHtOdpUCuF+7gSuG3yGIftsP1YvFihtJ8=
-github.com/stretchr/testify v1.8.2/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/xhit/go-str2duration/v2 v2.1.0 h1:lxklc02Drh6ynqX+DdPyp5pCKLUQpRT8bp8Ydu2Bstc=
 github.com/xhit/go-str2duration/v2 v2.1.0/go.mod h1:ohY8p+0f07DiV6Em5LKB0s2YpLtXVyJfNt1+BlmyAsU=
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
@@ -34,6 +28,4 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/ini.v1 v1.67.0 h1:Dgnx+6+nfE+IfzjUEISNeydPJh9AXNNsWbGP9KzCsOA=
 gopkg.in/ini.v1 v1.67.0/go.mod h1:pNLf8WUiyNEtQjuu5G5vTm06TEv9tsIgeAvK8hOrP4k=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
-gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/mail/mail.go b/mail/mail.go
index dfd8bf6..3b6bab4 100644
--- a/mail/mail.go
+++ b/mail/mail.go
@@ -3,11 +3,12 @@ package mail
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"os"
 	"strings"
 )
 
 type Email struct {
+	Path      string
 	Sender    string   `json:"sender"`
 	Receivers []string `json:"receivers"`
 	Subject   string   `json:"subject"`
@@ -26,9 +27,9 @@ func NewEmail(sender string, receivers []string, subject, content string) Email
 func FromJSON(path string) (Email, error) {
 	var mail Email
 
-	content, err := ioutil.ReadFile(path)
+	content, err := os.ReadFile(path)
 	if err != nil {
-		return mail, err
+		return mail, fmt.Errorf("%w, unable to read the file: %s", err, path)
 	}
 
 	if err := json.Unmarshal(content, &mail); err != nil {
diff --git a/services/sender.go b/services/sender.go
index 1ce0d7d..5e639b0 100644
--- a/services/sender.go
+++ b/services/sender.go
@@ -51,14 +51,14 @@ func (s Sender) SendMail(email mail.Email) error {
 	return nil
 }
 
-// watchOutbox reads the `outbox` directory every `TickInterval` and put JSON format e-mail in the queue
+// watchOutbox reads the `outbox` directory every `TickInterval` and put JSON format e-mail in the queue.
 func (s Sender) watchOutbox() {
 	log.Info().Str("outbox", s.outboxPath).Msg("start watching outbox directory")
 
 	ticker := time.NewTicker(TickerInterval)
 
 	go func() {
-		for _ = range ticker.C {
+		for range ticker.C {
 			log.Debug().Str("action", "retrieving json e-mail format...").Str("path", s.outboxPath)
 
 			files, err := os.ReadDir(s.outboxPath)
@@ -69,18 +69,34 @@ func (s Sender) watchOutbox() {
 
 			for _, file := range files {
 				filename := file.Name()
-				if strings.HasSuffix(filename, JSONSuffix) {
-					s.queue.Add(path.Join(s.outboxPath, filename))
+				if !strings.HasSuffix(filename, JSONSuffix) {
+					log.Debug().Str("filename", filename).Msg("incorrect suffix")
 					continue
 				}
 
-				log.Debug().Str("filename", filename).Msg("incorrect suffix")
+				path := path.Join(s.outboxPath, filename)
+				email, err := mail.FromJSON(path)
+
+				if err != nil {
+					log.Err(err).Str("path", path).Msg("unable to parse JSON email")
+
+					// if JSON parsing failed the `path` is renamed with an error suffix to not watch it again
+					newPath := fmt.Sprintf("%s%s", path, ErrorSuffix)
+					if err := os.Rename(path, newPath); err != nil {
+						log.Err(err).Str("path", path).Str("new path", newPath).Msg("unable to rename bad JSON email path")
+					}
+
+					continue
+				}
+
+				email.Path = path
+				s.queue.Add(email)
 			}
 		}
 	}()
 }
 
-// processNextEmail loops over the queue and send email
+// processNextEmail iterates over the queue and send email.
 func (s Sender) processNextEmail() bool {
 	item, quit := s.queue.Get()
 	if quit {
@@ -88,66 +104,56 @@ func (s Sender) processNextEmail() bool {
 	}
 	defer s.queue.Done(item)
 
-	path, ok := item.(string)
+	email, ok := item.(mail.Email)
 	if !ok {
 		log.Error().Any("item", item).Msg("unable to cast queue item into mail.Email")
 		return true
 	}
 
-	email, err := mail.FromJSON(path)
-	if err != nil {
-		log.Err(err).Str("path", path).Msg("unable to parse JSON email")
-
-		// if JSON parsing failed the `path` is renamed with an error suffix to avoid enqueued it again
-		newPath := fmt.Sprintf("%s%s", path, ErrorSuffix)
-		if err := os.Rename(path, newPath); err != nil {
-			log.Err(err).Str("path", path).Str("new path", newPath).Msg("unable to rename bad JSON email path")
-			s.queue.Shutdown()
-		}
-		return true
+	if err := s.SendMail(email); err != nil {
+		log.Err(err).Msg("unable to send the email")
 	}
 
-	// whatever the return, the email will be not enqueued again
-	s.SendMail(email)
-
-	if err := os.Remove(path); err != nil {
-		// this is a fatal error, can't send same e-mail indefinitely
-		if !os.IsExist(err) {
-			log.Err(err).Str("path", path).Msg("unable to remove the JSON email")
-			s.queue.Shutdown()
+	if path := email.Path; path != "" {
+		if err := os.Remove(path); err != nil {
+			// this is a fatal error, can't send same e-mail indefinitely
+			if !os.IsExist(err) {
+				log.Err(err).Str("path", path).Msg("unable to remove the JSON email")
+				s.queue.Shutdown()
+			}
 		}
 	}
 
 	return true
 }
 
-// run starts processing the queue
+// run starts processing the queue.
 func (s Sender) run() <-chan struct{} {
-	queueCh := make(chan struct{})
+	chQueue := make(chan struct{})
 	go func() {
 		for s.processNextEmail() {
 		}
-		queueCh <- struct{}{}
+		chQueue <- struct{}{}
 	}()
-	return queueCh
+	return chQueue
 }
 
-// Run launches the queue processing and the outbox watcher
-// catches `SIGINT` and `SIGTERM` to properly stopped the queue
+// Run launches the queue processing and the outbox watcher.
+// It catches `SIGINT` and `SIGTERM` to properly stopped the queue.
 func (s Sender) Run() {
 	log.Info().Msg("sender service is running")
 
-	sigCh := make(chan os.Signal, 1)
-	signal.Notify(sigCh, os.Interrupt, syscall.SIGTERM)
+	chSignal := make(chan os.Signal, 1)
+	signal.Notify(chSignal, os.Interrupt, syscall.SIGTERM)
 
 	s.watchOutbox()
-	queueCh := s.run()
+	chQueue := s.run()
 
 	select {
-	case <-sigCh:
+	case <-chSignal:
 		log.Warn().Msg("stop signal received, stopping e-mail queue...")
 		s.queue.Shutdown()
-	case <-queueCh:
+	case <-chQueue:
 		log.Info().Msg("e-mail queue stopped successfully")
 	}