diff --git a/README.md b/README.md
index 9edffa1..02ad361 100644
--- a/README.md
+++ b/README.md
@@ -193,6 +193,7 @@ To receive notifications by email, the following command-line options, or their
 * `--notification-email-from` (env. `WATCHTOWER_NOTIFICATION_EMAIL_FROM`): The e-mail address from which notifications will be sent.
 * `--notification-email-to` (env. `WATCHTOWER_NOTIFICATION_EMAIL_TO`): The e-mail address to which notifications will be sent.
 * `--notification-email-server` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER`): The SMTP server to send e-mails through.
+* `--notification-email-server-port` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PORT`): The port used to connect to the SMTP server to send e-mails through. Defaults to `25`.
 * `--notification-email-server-user` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER_USER`): The username to authenticate with the SMTP server with.
 * `--notification-email-server-password` (env. `WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PASSWORD`): The password to authenticate with the SMTP server with.
 
diff --git a/main.go b/main.go
index 89a7f5f..1fd015b 100644
--- a/main.go
+++ b/main.go
@@ -111,6 +111,12 @@ func main() {
 			Usage: "SMTP server to send notification e-mails through",
 			EnvVar: "WATCHTOWER_NOTIFICATION_EMAIL_SERVER",
 		},
+		cli.IntFlag{
+			Name: "notification-email-server-port",
+			Usage: "SMTP server port to send notification e-mails through",
+			Value:  25,
+			EnvVar: "WATCHTOWER_NOTIFICATION_EMAIL_SERVER_PORT",
+		},
 		cli.StringFlag{
 			Name: "notification-email-server-user",
 			Usage: "SMTP server user for sending notifications",
diff --git a/notifications/email.go b/notifications/email.go
index 9fd8774..c92a58f 100644
--- a/notifications/email.go
+++ b/notifications/email.go
@@ -6,6 +6,8 @@ import (
 	"net/smtp"
 	"os"
 
+	"strconv"
+
 	log "github.com/Sirupsen/logrus"
 	"github.com/urfave/cli"
 )
@@ -22,6 +24,7 @@ const (
 type emailTypeNotifier struct {
 	From, To               string
 	Server, User, Password string
+	Port                   int
 	entries                []*log.Entry
 }
 
@@ -32,6 +35,7 @@ func newEmailNotifier(c *cli.Context) typeNotifier {
 		Server:   c.GlobalString("notification-email-server"),
 		User:     c.GlobalString("notification-email-server-user"),
 		Password: c.GlobalString("notification-email-server-password"),
+		Port:     c.GlobalInt("notification-email-server-port"),
 	}
 
 	log.AddHook(n)
@@ -72,7 +76,7 @@ func (e *emailTypeNotifier) sendEntries(entries []*log.Entry) {
 	msg := e.buildMessage(entries)
 	go func() {
 		auth := smtp.PlainAuth("", e.User, e.Password, e.Server)
-		err := smtp.SendMail(e.Server+":25", auth, e.From, []string{e.To}, msg)
+		err := smtp.SendMail(e.Server+":"+strconv.Itoa(e.Port), auth, e.From, []string{e.To}, msg)
 		if err != nil {
 			// Use fmt so it doesn't trigger another email.
 			fmt.Println("Failed to send notification email: ", err)