feat: add SMTP email service with signature reminders

Add configurable SMTP service for sending signature reminder emails.

Features:
- Configurable via ACKIFY_MAIL_* environment variables
- Multilingual templates (en/fr) with HTML + text versions
- Template rendering with automatic variable injection
- Graceful degradation when SMTP not configured
- TLS/STARTTLS support with configurable timeout
- MailHog integration for local testing

go.mod

@@ -4,12 +4,14 @@ go 1.24.5
 
 require (
 	github.com/go-chi/chi/v5 v5.2.3
+	github.com/go-mail/mail/v2 v2.3.0
 	github.com/golang-migrate/migrate/v4 v4.19.0
 	github.com/gorilla/securecookie v1.1.2
 	github.com/gorilla/sessions v1.4.0
 	github.com/lib/pq v1.10.9
 	github.com/stretchr/testify v1.11.1
 	golang.org/x/oauth2 v0.31.0
+	golang.org/x/text v0.29.0
 )
 
 require (
@@ -19,7 +21,8 @@ require (
 	github.com/kr/pretty v0.3.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rogpeppe/go-internal v1.13.1 // indirect
-	golang.org/x/text v0.29.0 // indirect
+	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect
 	gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c // indirect
+	gopkg.in/mail.v2 v2.3.1 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -27,6 +27,8 @@ github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
 github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
 github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
 github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
+github.com/go-mail/mail/v2 v2.3.0 h1:wha99yf2v3cpUzD1V9ujP404Jbw2uEvs+rBJybkdYcw=
+github.com/go-mail/mail/v2 v2.3.0/go.mod h1:oE2UK8qebZAjjV1ZYUpY7FPnbi/kIU53l1dmqPRb4go=
 github.com/gogo/protobuf v1.3.2 h1:Ov1cvc58UF3b5XjBnZv7+opcTcQFZebYjWzi34vdm4Q=
 github.com/gogo/protobuf v1.3.2/go.mod h1:P1XiOD3dCwIKUDQYPy72D8LYyHL2YPYrpS2s69NZV8Q=
 github.com/golang-migrate/migrate/v4 v4.19.0 h1:RcjOnCGz3Or6HQYEJ/EEVLfWnmw9KnoigPSjzhCuaSE=
@@ -87,8 +89,12 @@ golang.org/x/sys v0.31.0 h1:ioabZlmFYtWhL+TRYpcnNlLwhyxaM9kWTDEmfnprqik=
 golang.org/x/sys v0.31.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
 golang.org/x/text v0.29.0 h1:1neNs90w9YzJ9BocxfsQNHKuAT4pkghyXc4nhZ6sJvk=
 golang.org/x/text v0.29.0/go.mod h1:7MhJOA9CD2qZyOKYazxdYMF85OwPdEr9jTtBpO7ydH4=
+gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc h1:2gGKlE2+asNV9m7xrywl36YYNnBG5ZQ0r/BOOxqPpmk=
+gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc/go.mod h1:m7x9LTH6d71AHyAX77c9yqWCCa3UKHcVEj9y7hAtKDk=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EVd6muEfDQjcINNoR0C8j2r3qZ4Q=
+gopkg.in/mail.v2 v2.3.1 h1:WYFn/oANrAGP2C0dcV6/pbkPzv8yGzqTjPmTeO7qoXk=
+gopkg.in/mail.v2 v2.3.1/go.mod h1:htwXN1Qh09vZJ1NVKxQqHPBaCBbzKhp5GzuJEA4VJWw=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/infrastructure/config/config.go

@@ -16,6 +16,7 @@ type Config struct {
 	OAuth    OAuthConfig
 	Server   ServerConfig
 	Logger   LoggerConfig
+	Mail     MailConfig
 }
 
 type AppConfig struct {
@@ -50,6 +51,21 @@ type LoggerConfig struct {
 	Level string
 }
 
+type MailConfig struct {
+	Host          string
+	Port          int
+	Username      string
+	Password      string
+	TLS           bool
+	StartTLS      bool
+	Timeout       string
+	From          string
+	FromName      string
+	SubjectPrefix string
+	TemplateDir   string
+	DefaultLocale string
+}
+
 // Load loads configuration from environment variables
 func Load() (*Config, error) {
 	config := &Config{}
@@ -118,6 +134,23 @@ func Load() (*Config, error) {
 		}
 	}
 
+	// Parse mail config (optional, service disabled if MAIL_HOST not set)
+	mailHost := getEnv("ACKIFY_MAIL_HOST", "")
+	if mailHost != "" {
+		config.Mail.Host = mailHost
+		config.Mail.Port = getEnvInt("ACKIFY_MAIL_PORT", 587)
+		config.Mail.Username = getEnv("ACKIFY_MAIL_USERNAME", "")
+		config.Mail.Password = getEnv("ACKIFY_MAIL_PASSWORD", "")
+		config.Mail.TLS = getEnvBool("ACKIFY_MAIL_TLS", true)
+		config.Mail.StartTLS = getEnvBool("ACKIFY_MAIL_STARTTLS", true)
+		config.Mail.Timeout = getEnv("ACKIFY_MAIL_TIMEOUT", "10s")
+		config.Mail.From = getEnv("ACKIFY_MAIL_FROM", "")
+		config.Mail.FromName = getEnv("ACKIFY_MAIL_FROM_NAME", config.App.Organisation)
+		config.Mail.SubjectPrefix = getEnv("ACKIFY_MAIL_SUBJECT_PREFIX", "")
+		config.Mail.TemplateDir = getEnv("ACKIFY_MAIL_TEMPLATE_DIR", "templates/emails")
+		config.Mail.DefaultLocale = getEnv("ACKIFY_MAIL_DEFAULT_LOCALE", "en")
+	}
+
 	return config, nil
 }
 
@@ -151,3 +184,23 @@ func parseCookieSecret() ([]byte, error) {
 
 	return []byte(raw), nil
 }
+
+func getEnvInt(key string, defaultValue int) int {
+	value := strings.TrimSpace(os.Getenv(key))
+	if value == "" {
+		return defaultValue
+	}
+	var result int
+	if _, err := fmt.Sscanf(value, "%d", &result); err == nil {
+		return result
+	}
+	return defaultValue
+}
+
+func getEnvBool(key string, defaultValue bool) bool {
+	value := strings.TrimSpace(os.Getenv(key))
+	if value == "" {
+		return defaultValue
+	}
+	return strings.ToLower(value) == "true" || value == "1"
+}

internal/infrastructure/config/config_test.go

@@ -933,3 +933,273 @@ func equalSlices(a, b []string) bool {
 	}
 	return true
 }
+
+func TestLoad_MailConfig(t *testing.T) {
+	t.Run("mail config with all settings", func(t *testing.T) {
+		envVars := map[string]string{
+			"ACKIFY_BASE_URL":            "https://ackify.example.com",
+			"ACKIFY_ORGANISATION":        "Test Org",
+			"ACKIFY_DB_DSN":              "postgres://user:pass@localhost/test",
+			"ACKIFY_OAUTH_CLIENT_ID":     "test-client-id",
+			"ACKIFY_OAUTH_CLIENT_SECRET": "test-client-secret",
+			"ACKIFY_OAUTH_PROVIDER":      "google",
+			"ACKIFY_MAIL_HOST":           "smtp.example.com",
+			"ACKIFY_MAIL_PORT":           "465",
+			"ACKIFY_MAIL_USERNAME":       "noreply@example.com",
+			"ACKIFY_MAIL_PASSWORD":       "smtp-password",
+			"ACKIFY_MAIL_TLS":            "true",
+			"ACKIFY_MAIL_STARTTLS":       "false",
+			"ACKIFY_MAIL_TIMEOUT":        "30s",
+			"ACKIFY_MAIL_FROM":           "noreply@example.com",
+			"ACKIFY_MAIL_FROM_NAME":      "Ackify Notifications",
+			"ACKIFY_MAIL_SUBJECT_PREFIX": "[Ackify]",
+			"ACKIFY_MAIL_TEMPLATE_DIR":   "/custom/templates/emails",
+			"ACKIFY_MAIL_DEFAULT_LOCALE": "fr",
+		}
+
+		for key, value := range envVars {
+			_ = os.Setenv(key, value)
+		}
+		defer func() {
+			for key := range envVars {
+				_ = os.Unsetenv(key)
+			}
+		}()
+
+		config, err := Load()
+		if err != nil {
+			t.Fatalf("Load() failed: %v", err)
+		}
+
+		if config.Mail.Host != "smtp.example.com" {
+			t.Errorf("Mail.Host = %v, expected smtp.example.com", config.Mail.Host)
+		}
+		if config.Mail.Port != 465 {
+			t.Errorf("Mail.Port = %v, expected 465", config.Mail.Port)
+		}
+		if config.Mail.Username != "noreply@example.com" {
+			t.Errorf("Mail.Username = %v, expected noreply@example.com", config.Mail.Username)
+		}
+		if config.Mail.Password != "smtp-password" {
+			t.Errorf("Mail.Password = %v, expected smtp-password", config.Mail.Password)
+		}
+		if !config.Mail.TLS {
+			t.Error("Mail.TLS should be true")
+		}
+		if config.Mail.StartTLS {
+			t.Error("Mail.StartTLS should be false")
+		}
+		if config.Mail.Timeout != "30s" {
+			t.Errorf("Mail.Timeout = %v, expected 30s", config.Mail.Timeout)
+		}
+		if config.Mail.From != "noreply@example.com" {
+			t.Errorf("Mail.From = %v, expected noreply@example.com", config.Mail.From)
+		}
+		if config.Mail.FromName != "Ackify Notifications" {
+			t.Errorf("Mail.FromName = %v, expected Ackify Notifications", config.Mail.FromName)
+		}
+		if config.Mail.SubjectPrefix != "[Ackify]" {
+			t.Errorf("Mail.SubjectPrefix = %v, expected [Ackify]", config.Mail.SubjectPrefix)
+		}
+		if config.Mail.TemplateDir != "/custom/templates/emails" {
+			t.Errorf("Mail.TemplateDir = %v, expected /custom/templates/emails", config.Mail.TemplateDir)
+		}
+		if config.Mail.DefaultLocale != "fr" {
+			t.Errorf("Mail.DefaultLocale = %v, expected fr", config.Mail.DefaultLocale)
+		}
+	})
+
+	t.Run("mail config with defaults", func(t *testing.T) {
+		envVars := map[string]string{
+			"ACKIFY_BASE_URL":            "https://ackify.example.com",
+			"ACKIFY_ORGANISATION":        "Test Org",
+			"ACKIFY_DB_DSN":              "postgres://user:pass@localhost/test",
+			"ACKIFY_OAUTH_CLIENT_ID":     "test-client-id",
+			"ACKIFY_OAUTH_CLIENT_SECRET": "test-client-secret",
+			"ACKIFY_OAUTH_PROVIDER":      "google",
+			"ACKIFY_MAIL_HOST":           "smtp.example.com",
+		}
+
+		for key, value := range envVars {
+			_ = os.Setenv(key, value)
+		}
+		defer func() {
+			for key := range envVars {
+				_ = os.Unsetenv(key)
+			}
+		}()
+
+		config, err := Load()
+		if err != nil {
+			t.Fatalf("Load() failed: %v", err)
+		}
+
+		if config.Mail.Port != 587 {
+			t.Errorf("Mail.Port = %v, expected default 587", config.Mail.Port)
+		}
+		if !config.Mail.TLS {
+			t.Error("Mail.TLS should default to true")
+		}
+		if !config.Mail.StartTLS {
+			t.Error("Mail.StartTLS should default to true")
+		}
+		if config.Mail.Timeout != "10s" {
+			t.Errorf("Mail.Timeout = %v, expected default 10s", config.Mail.Timeout)
+		}
+		if config.Mail.FromName != "Test Org" {
+			t.Errorf("Mail.FromName = %v, expected organisation name", config.Mail.FromName)
+		}
+		if config.Mail.TemplateDir != "templates/emails" {
+			t.Errorf("Mail.TemplateDir = %v, expected default templates/emails", config.Mail.TemplateDir)
+		}
+		if config.Mail.DefaultLocale != "en" {
+			t.Errorf("Mail.DefaultLocale = %v, expected default en", config.Mail.DefaultLocale)
+		}
+	})
+
+	t.Run("mail disabled when MAIL_HOST not set", func(t *testing.T) {
+		envVars := map[string]string{
+			"ACKIFY_BASE_URL":            "https://ackify.example.com",
+			"ACKIFY_ORGANISATION":        "Test Org",
+			"ACKIFY_DB_DSN":              "postgres://user:pass@localhost/test",
+			"ACKIFY_OAUTH_CLIENT_ID":     "test-client-id",
+			"ACKIFY_OAUTH_CLIENT_SECRET": "test-client-secret",
+			"ACKIFY_OAUTH_PROVIDER":      "google",
+		}
+
+		for key, value := range envVars {
+			_ = os.Setenv(key, value)
+		}
+		defer func() {
+			for key := range envVars {
+				_ = os.Unsetenv(key)
+			}
+		}()
+
+		_ = os.Unsetenv("ACKIFY_MAIL_HOST")
+
+		config, err := Load()
+		if err != nil {
+			t.Fatalf("Load() failed: %v", err)
+		}
+
+		if config.Mail.Host != "" {
+			t.Errorf("Mail.Host should be empty when not configured, got %v", config.Mail.Host)
+		}
+		if config.Mail.Port != 0 {
+			t.Errorf("Mail.Port should be 0 when not configured, got %v", config.Mail.Port)
+		}
+	})
+}
+
+func TestGetEnvInt(t *testing.T) {
+	tests := []struct {
+		name         string
+		key          string
+		envValue     string
+		defaultValue int
+		expected     int
+	}{
+		{
+			name:         "valid integer",
+			key:          "TEST_INT_VAR",
+			envValue:     "587",
+			defaultValue: 25,
+			expected:     587,
+		},
+		{
+			name:         "missing uses default",
+			key:          "MISSING_INT_VAR",
+			envValue:     "",
+			defaultValue: 100,
+			expected:     100,
+		},
+		{
+			name:         "invalid integer uses default",
+			key:          "INVALID_INT_VAR",
+			envValue:     "not-a-number",
+			defaultValue: 50,
+			expected:     50,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_ = os.Unsetenv(tt.key)
+			if tt.envValue != "" {
+				_ = os.Setenv(tt.key, tt.envValue)
+				defer func() {
+					_ = os.Unsetenv(tt.key)
+				}()
+			}
+
+			result := getEnvInt(tt.key, tt.defaultValue)
+			if result != tt.expected {
+				t.Errorf("getEnvInt() = %v, expected %v", result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestGetEnvBool(t *testing.T) {
+	tests := []struct {
+		name         string
+		key          string
+		envValue     string
+		defaultValue bool
+		expected     bool
+	}{
+		{
+			name:         "true string",
+			key:          "TEST_BOOL_VAR",
+			envValue:     "true",
+			defaultValue: false,
+			expected:     true,
+		},
+		{
+			name:         "1 string",
+			key:          "TEST_BOOL_VAR",
+			envValue:     "1",
+			defaultValue: false,
+			expected:     true,
+		},
+		{
+			name:         "false string",
+			key:          "TEST_BOOL_VAR",
+			envValue:     "false",
+			defaultValue: true,
+			expected:     false,
+		},
+		{
+			name:         "missing uses default true",
+			key:          "MISSING_BOOL_VAR",
+			envValue:     "",
+			defaultValue: true,
+			expected:     true,
+		},
+		{
+			name:         "missing uses default false",
+			key:          "MISSING_BOOL_VAR",
+			envValue:     "",
+			defaultValue: false,
+			expected:     false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_ = os.Unsetenv(tt.key)
+			if tt.envValue != "" {
+				_ = os.Setenv(tt.key, tt.envValue)
+				defer func() {
+					_ = os.Unsetenv(tt.key)
+				}()
+			}
+
+			result := getEnvBool(tt.key, tt.defaultValue)
+			if result != tt.expected {
+				t.Errorf("getEnvBool() = %v, expected %v", result, tt.expected)
+			}
+		})
+	}
+}

internal/infrastructure/email/helpers.go

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+package email
+
+import (
+	"context"
+)
+
+func SendEmail(ctx context.Context, sender Sender, template string, to []string, locale string, subject string, data map[string]any) error {
+	msg := Message{
+		To:       to,
+		Subject:  subject,
+		Template: template,
+		Locale:   locale,
+		Data:     data,
+	}
+
+	return sender.Send(ctx, msg)
+}
+
+func SendSignatureReminderEmail(ctx context.Context, sender Sender, to []string, locale, docID, docURL, signURL string) error {
+	data := map[string]any{
+		"DocID":   docID,
+		"DocURL":  docURL,
+		"SignURL": signURL,
+	}
+
+	subject := "Reminder: Document signature required"
+	if locale == "fr" {
+		subject = "Rappel : Signature de document requise"
+	}
+
+	return SendEmail(ctx, sender, "signature_reminder", to, locale, subject, data)
+}

internal/infrastructure/email/renderer.go

@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+package email
+
+import (
+	"bytes"
+	"fmt"
+	htmlTemplate "html/template"
+	"os"
+	"path/filepath"
+	txtTemplate "text/template"
+)
+
+type Renderer struct {
+	templateDir   string
+	baseURL       string
+	organisation  string
+	fromName      string
+	fromMail      string
+	defaultLocale string
+}
+
+type TemplateData struct {
+	Organisation string
+	BaseURL      string
+	FromName     string
+	FromMail     string
+	Data         map[string]any
+}
+
+func NewRenderer(templateDir, baseURL, organisation, fromName, fromMail, defaultLocale string) *Renderer {
+	return &Renderer{
+		templateDir:   templateDir,
+		baseURL:       baseURL,
+		organisation:  organisation,
+		fromName:      fromName,
+		fromMail:      fromMail,
+		defaultLocale: defaultLocale,
+	}
+}
+
+func (r *Renderer) Render(templateName, locale string, data map[string]any) (htmlBody, textBody string, err error) {
+	if locale == "" {
+		locale = r.defaultLocale
+	}
+
+	templateData := TemplateData{
+		Organisation: r.organisation,
+		BaseURL:      r.baseURL,
+		FromName:     r.fromName,
+		FromMail:     r.fromMail,
+		Data:         data,
+	}
+
+	htmlBody, err = r.renderHTML(templateName, locale, templateData)
+	if err != nil {
+		return "", "", fmt.Errorf("failed to render HTML: %w", err)
+	}
+
+	textBody, err = r.renderText(templateName, locale, templateData)
+	if err != nil {
+		return "", "", fmt.Errorf("failed to render text: %w", err)
+	}
+
+	return htmlBody, textBody, nil
+}
+
+func (r *Renderer) renderHTML(templateName, locale string, data TemplateData) (string, error) {
+	baseTemplatePath := filepath.Join(r.templateDir, "base.html.tmpl")
+	templatePath := r.resolveTemplatePath(templateName, locale, "html.tmpl")
+
+	if templatePath == "" {
+		return "", fmt.Errorf("template not found: %s (locale: %s)", templateName, locale)
+	}
+
+	tmpl, err := htmlTemplate.ParseFiles(baseTemplatePath, templatePath)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse template: %w", err)
+	}
+
+	var buf bytes.Buffer
+	if err := tmpl.ExecuteTemplate(&buf, "base", data); err != nil {
+		return "", fmt.Errorf("failed to execute template: %w", err)
+	}
+
+	return buf.String(), nil
+}
+
+func (r *Renderer) renderText(templateName, locale string, data TemplateData) (string, error) {
+	baseTemplatePath := filepath.Join(r.templateDir, "base.txt.tmpl")
+	templatePath := r.resolveTemplatePath(templateName, locale, "txt.tmpl")
+
+	if templatePath == "" {
+		return "", fmt.Errorf("template not found: %s (locale: %s)", templateName, locale)
+	}
+
+	tmpl, err := txtTemplate.ParseFiles(baseTemplatePath, templatePath)
+	if err != nil {
+		return "", fmt.Errorf("failed to parse template: %w", err)
+	}
+
+	var buf bytes.Buffer
+	if err := tmpl.ExecuteTemplate(&buf, "base", data); err != nil {
+		return "", fmt.Errorf("failed to execute template: %w", err)
+	}
+
+	return buf.String(), nil
+}
+
+func (r *Renderer) resolveTemplatePath(templateName, locale, extension string) string {
+	localizedPath := filepath.Join(r.templateDir, fmt.Sprintf("%s.%s.%s", templateName, locale, extension))
+	if _, err := os.Stat(localizedPath); err == nil {
+		return localizedPath
+	}
+
+	fallbackPath := filepath.Join(r.templateDir, fmt.Sprintf("%s.en.%s", templateName, extension))
+	if _, err := os.Stat(fallbackPath); err == nil {
+		return fallbackPath
+	}
+
+	return ""
+}

internal/infrastructure/email/sender.go

@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+package email
+
+import (
+	"context"
+	"crypto/tls"
+	"fmt"
+	"time"
+
+	mail "github.com/go-mail/mail/v2"
+
+	"github.com/btouchard/ackify-ce/internal/infrastructure/config"
+	"github.com/btouchard/ackify-ce/pkg/logger"
+)
+
+type Sender interface {
+	Send(ctx context.Context, msg Message) error
+}
+
+type Message struct {
+	To       []string
+	Cc       []string
+	Bcc      []string
+	Subject  string
+	Template string
+	Locale   string
+	Data     map[string]any
+	Headers  map[string]string
+}
+
+type SMTPSender struct {
+	config   config.MailConfig
+	renderer *Renderer
+}
+
+func NewSMTPSender(cfg config.MailConfig, renderer *Renderer) *SMTPSender {
+	return &SMTPSender{
+		config:   cfg,
+		renderer: renderer,
+	}
+}
+
+func (s *SMTPSender) Send(ctx context.Context, msg Message) error {
+	if s.config.Host == "" {
+		logger.Logger.Info("SMTP not configured, email not sent", "template", msg.Template)
+		return nil
+	}
+
+	htmlBody, textBody, err := s.renderer.Render(msg.Template, msg.Locale, msg.Data)
+	if err != nil {
+		return fmt.Errorf("failed to render email template: %w", err)
+	}
+
+	m := mail.NewMessage()
+
+	from := s.config.From
+	if from == "" {
+		return fmt.Errorf("ACKIFY_MAIL_FROM not set")
+	}
+	m.SetHeader("From", m.FormatAddress(from, s.config.FromName))
+
+	if len(msg.To) == 0 {
+		return fmt.Errorf("no recipients specified")
+	}
+	m.SetHeader("To", msg.To...)
+
+	if len(msg.Cc) > 0 {
+		m.SetHeader("Cc", msg.Cc...)
+	}
+
+	if len(msg.Bcc) > 0 {
+		m.SetHeader("Bcc", msg.Bcc...)
+	}
+
+	subject := msg.Subject
+	if s.config.SubjectPrefix != "" {
+		subject = s.config.SubjectPrefix + subject
+	}
+	m.SetHeader("Subject", subject)
+
+	for key, value := range msg.Headers {
+		m.SetHeader(key, value)
+	}
+
+	m.SetBody("text/plain", textBody)
+	m.AddAlternative("text/html", htmlBody)
+
+	timeout, err := time.ParseDuration(s.config.Timeout)
+	if err != nil {
+		timeout = 10 * time.Second
+	}
+
+	d := mail.NewDialer(s.config.Host, s.config.Port, s.config.Username, s.config.Password)
+
+	if s.config.TLS {
+		d.SSL = true
+	}
+
+	if s.config.StartTLS {
+		d.TLSConfig = &tls.Config{ServerName: s.config.Host}
+	}
+
+	d.Timeout = timeout
+
+	logger.Logger.Info("Sending email", "to", msg.To, "template", msg.Template, "locale", msg.Locale)
+
+	if err := d.DialAndSend(m); err != nil {
+		return fmt.Errorf("failed to send email: %w", err)
+	}
+
+	logger.Logger.Info("Email sent successfully", "to", msg.To)
+	return nil
+}

templates/emails/base.html.tmpl

@@ -0,0 +1,61 @@
+{{define "base"}}
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>{{.Organisation}}</title>
+    <style>
+        body {
+            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
+            line-height: 1.6;
+            color: #333;
+            max-width: 600px;
+            margin: 0 auto;
+            padding: 20px;
+        }
+        .header {
+            border-bottom: 2px solid #4F46E5;
+            padding-bottom: 20px;
+            margin-bottom: 30px;
+        }
+        .header h1 {
+            color: #4F46E5;
+            margin: 0;
+            font-size: 24px;
+        }
+        .content {
+            margin-bottom: 30px;
+        }
+        .footer {
+            border-top: 1px solid #e5e7eb;
+            padding-top: 20px;
+            margin-top: 30px;
+            font-size: 14px;
+            color: #6b7280;
+        }
+        a {
+            color: #4F46E5;
+            text-decoration: none;
+        }
+        a:hover {
+            text-decoration: underline;
+        }
+    </style>
+</head>
+<body>
+    <div class="header">
+        <h1>{{.Organisation}}</h1>
+    </div>
+
+    <div class="content">
+        {{template "content" .}}
+    </div>
+
+    <div class="footer">
+        <p>This email was sent by <a href="{{.BaseURL}}">{{.Organisation}}</a></p>
+        <p>Powered by Ackify - Proof of Read</p>
+    </div>
+</body>
+</html>
+{{end}}

templates/emails/base.txt.tmpl

@@ -0,0 +1,13 @@
+{{define "base"}}
+========================================
+{{.Organisation}}
+========================================
+
+{{template "content" .}}
+
+----------------------------------------
+This email was sent by {{.Organisation}}
+{{.BaseURL}}
+
+Powered by Ackify - Proof of Read
+{{end}}

templates/emails/signature_reminder.en.html.tmpl

@@ -0,0 +1,29 @@
+{{define "content"}}
+<h2>Document Signature Reminder</h2>
+
+<p>Hello,</p>
+
+<p>This is a reminder that the following document requires your signature:</p>
+
+<div style="background-color: #f3f4f6; padding: 15px; border-radius: 8px; margin: 20px 0;">
+    <p style="margin: 0;"><strong>Document ID:</strong> {{.Data.DocID}}</p>
+</div>
+
+<p>To review and sign this document, please follow these steps:</p>
+
+<ol>
+    <li>Review the document at: <a href="{{.Data.DocURL}}">{{.Data.DocURL}}</a></li>
+    <li>Sign the document at: <a href="{{.Data.SignURL}}">{{.Data.SignURL}}</a></li>
+</ol>
+
+<div style="margin: 30px 0;">
+    <a href="{{.Data.SignURL}}" style="background-color: #4F46E5; color: white; padding: 12px 24px; text-decoration: none; border-radius: 6px; display: inline-block;">Sign Document Now</a>
+</div>
+
+<p>Your cryptographic signature will provide verifiable proof that you have read and acknowledged this document.</p>
+
+<p>If you have any questions, please contact your administrator.</p>
+
+<p>Best regards,<br>
+The {{.Organisation}} Team</p>
+{{end}}

templates/emails/signature_reminder.en.txt.tmpl

@@ -0,0 +1,21 @@
+{{define "content"}}
+Document Signature Reminder
+
+Hello,
+
+This is a reminder that the following document requires your signature:
+
+Document ID: {{.Data.DocID}}
+
+To review and sign this document, please follow these steps:
+
+1. Review the document at: {{.Data.DocURL}}
+2. Sign the document at: {{.Data.SignURL}}
+
+Your cryptographic signature will provide verifiable proof that you have read and acknowledged this document.
+
+If you have any questions, please contact your administrator.
+
+Best regards,
+The {{.Organisation}} Team
+{{end}}

templates/emails/signature_reminder.fr.html.tmpl

@@ -0,0 +1,29 @@
+{{define "content"}}
+<h2>Rappel de signature de document</h2>
+
+<p>Bonjour,</p>
+
+<p>Ceci est un rappel que le document suivant nécessite votre signature :</p>
+
+<div style="background-color: #f3f4f6; padding: 15px; border-radius: 8px; margin: 20px 0;">
+    <p style="margin: 0;"><strong>ID du document :</strong> {{.Data.DocID}}</p>
+</div>
+
+<p>Pour consulter et signer ce document, veuillez suivre ces étapes :</p>
+
+<ol>
+    <li>Consulter le document à : <a href="{{.Data.DocURL}}">{{.Data.DocURL}}</a></li>
+    <li>Signer le document à : <a href="{{.Data.SignURL}}">{{.Data.SignURL}}</a></li>
+</ol>
+
+<div style="margin: 30px 0;">
+    <a href="{{.Data.SignURL}}" style="background-color: #4F46E5; color: white; padding: 12px 24px; text-decoration: none; border-radius: 6px; display: inline-block;">Signer le document maintenant</a>
+</div>
+
+<p>Votre signature cryptographique fournira une preuve vérifiable que vous avez lu et pris connaissance de ce document.</p>
+
+<p>Si vous avez des questions, veuillez contacter votre administrateur.</p>
+
+<p>Cordialement,<br>
+L'équipe {{.Organisation}}</p>
+{{end}}

templates/emails/signature_reminder.fr.txt.tmpl

@@ -0,0 +1,21 @@
+{{define "content"}}
+Rappel de signature de document
+
+Bonjour,
+
+Ceci est un rappel que le document suivant nécessite votre signature :
+
+ID du document : {{.Data.DocID}}
+
+Pour consulter et signer ce document, veuillez suivre ces étapes :
+
+1. Consulter le document à : {{.Data.DocURL}}
+2. Signer le document à : {{.Data.SignURL}}
+
+Votre signature cryptographique fournira une preuve vérifiable que vous avez lu et pris connaissance de ce document.
+
+Si vous avez des questions, veuillez contacter votre administrateur.
+
+Cordialement,
+L'équipe {{.Organisation}}
+{{end}}