diff --git a/cmd/api/main.go b/cmd/api/main.go
index c57a426..4e3894f 100644
--- a/cmd/api/main.go
+++ b/cmd/api/main.go
@@ -6,9 +6,12 @@ import (
 	"flag"
 	"log/slog"
 	"os"
+	"strconv"
 	"time"
 
+	"github.com/joho/godotenv"
 	"greenlight.craftr.fr/internal/data"
+	"greenlight.craftr.fr/internal/mailer"
 
 	// Import the pq driver so that it can register itself with the database/sql package. Note that we alias this import to the blank identifier, to stop the Go compiler complaining that the package isn't being used.
 	_ "github.com/lib/pq"
@@ -44,6 +47,13 @@ type config struct {
 		burst   int
 		enabled bool
 	}
+	smtp struct {
+		host     string
+		port     int
+		username string
+		password string
+		sender   string
+	}
 }
 
 // application struct hold the dependencies for our HTTP handlers, helpers, and middleware.
@@ -51,9 +61,18 @@ type application struct {
 	config config
 	logger *slog.Logger
 	models data.Models
+	mailer mailer.Mailer
 }
 
 func main() {
+	// Initialize a new structured logger which writes log entries to standard out stream.
+	logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
+
+	err := godotenv.Load()
+	if err != nil {
+		logger.Error("Error loading .env file")
+	}
+
 	// Declare an instance of the config struct.
 	var cfg config
 
@@ -78,10 +97,24 @@ func main() {
 	flag.IntVar(&cfg.limiter.burst, "limiter-burst", 4, "Rate limiter maximum burst")
 	flag.BoolVar(&cfg.limiter.enabled, "limiter-enabled", true, "Enable rate limiter")
 
-	flag.Parse()
+	smtpHost := os.Getenv("SMTP_HOST")
+	smtpPort := os.Getenv("SMTP_PORT")
+	smtpPortInt, err := strconv.Atoi(smtpPort)
+	if err != nil {
+		logger.Error("couldn't convert smtpPort to integer.")
+	}
+	smtpUsername := os.Getenv("SMTP_USERNAME")
+	smtpPassword := os.Getenv("SMTP_PASSWORD")
+	smtpSender := os.Getenv("SMTP_SENDER")
 
-	// Initialize a new structured logger which writes log entries to standard out stream.
-	logger := slog.New(slog.NewTextHandler(os.Stdout, nil))
+	// Read the SMTP server configuration settings into the config struct, using the Mailtrap settings as the default values.
+	flag.StringVar(&cfg.smtp.host, "smtp-host", smtpHost, "SMTP host")
+	flag.IntVar(&cfg.smtp.port, "smtp-port", smtpPortInt, "SMTP port")
+	flag.StringVar(&cfg.smtp.username, "smtp-username", smtpUsername, "SMTP username")
+	flag.StringVar(&cfg.smtp.password, "smtp-password", smtpPassword, "SMTP password")
+	flag.StringVar(&cfg.smtp.sender, "smtp-sender", smtpSender, "SMTP sender")
+
+	flag.Parse()
 
 	// Call the openDB() helper function to create the connection pool, passing in the config struct. If this returns an error, we log it and exit the application immediately.
 	db, err := openDB(cfg)
@@ -101,6 +134,7 @@ func main() {
 		config: cfg,
 		logger: logger,
 		models: data.NewModels(db),
+		mailer: mailer.New(cfg.smtp.host, cfg.smtp.port, cfg.smtp.username, cfg.smtp.password, cfg.smtp.sender),
 	}
 
 	// Call app.serve() to start the server.
diff --git a/cmd/api/users.go b/cmd/api/users.go
index b74be07..1d3fce1 100644
--- a/cmd/api/users.go
+++ b/cmd/api/users.go
@@ -59,6 +59,13 @@ func (app *application) registerUserHandler(w http.ResponseWriter, r *http.Reque
 		return
 	}
 
+	// Call the Send() method on our Mail, passing in the user's email address, name of the template file, and the User struct containing the new user's data.
+	err = app.mailer.Send(user.Email, "user_welcome.tmpl", user)
+	if err != nil {
+		app.serverErrorResponse(w, r, err)
+		return
+	}
+
 	// Write a JSON response containing the user data along with a 201 Created status code
 	err = app.writeJSON(w, http.StatusCreated, envelope{"user": user}, nil)
 	if err != nil {
diff --git a/go.mod b/go.mod
index 1057413..7ed9f92 100644
--- a/go.mod
+++ b/go.mod
@@ -4,6 +4,7 @@ go 1.25.1
 
 require (
 	github.com/go-mail/mail/v2 v2.3.0 // indirect
+	github.com/joho/godotenv v1.5.1 // indirect
 	github.com/julienschmidt/httprouter v1.3.0 // indirect
 	github.com/lib/pq v1.10.9 // indirect
 	golang.org/x/crypto v0.45.0 // indirect
diff --git a/go.sum b/go.sum
index 9e6fc28..8cf96f9 100644
--- a/go.sum
+++ b/go.sum
@@ -1,5 +1,7 @@
 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/joho/godotenv v1.5.1 h1:7eLL/+HRGLY0ldzfGMeQkb7vMd0as4CfYvUVzLqw0N0=
+github.com/joho/godotenv v1.5.1/go.mod h1:f4LDr5Voq0i2e/R5DDNOoa2zzDfwtkZa6DnEwAbqwq4=
 github.com/julienschmidt/httprouter v1.3.0 h1:U0609e9tgbseu3rBINet9P48AI/D3oJs4dN7jwJOQ1U=
 github.com/julienschmidt/httprouter v1.3.0/go.mod h1:JR6WtHb+2LUe8TCKY3cZOxFyyO8IZAc4RVcycCCAKdM=
 github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=