diff --git a/internal/engine/experiment/smtp/smtp.go b/internal/engine/experiment/smtp/smtp.go
index 97c183f..568db04 100644
--- a/internal/engine/experiment/smtp/smtp.go
+++ b/internal/engine/experiment/smtp/smtp.go
@@ -8,7 +8,6 @@ import (
 	"net"
 	"net/smtp"
 	"net/url"
-	"strconv"
 	"time"
 
 	"github.com/ooni/probe-cli/v3/internal/engine/experiment/urlgetter"
@@ -26,9 +25,6 @@ var (
 
 	// errInvalidScheme indicates that the scheme is invalid
 	errInvalidScheme = errors.New("scheme must be smtp(s)")
-
-	// errInvalidPort indicates that the port provided could not be parsed as an int
-	errInvalidPort = errors.New("Port number is not a valid integer")
 )
 
 const (
@@ -37,14 +33,16 @@ const (
 )
 
 // Config contains the experiment config.
-type Config struct {
+type Config struct{}
+
+type RuntimeConfig struct {
 	host       string
 	port       string
 	forced_tls bool
 	noop_count uint8
 }
 
-func config(input model.MeasurementTarget) (*Config, error) {
+func config(input model.MeasurementTarget) (*RuntimeConfig, error) {
 	if input == "" {
 		// TODO: static input data (eg. gmail/riseup..)
 		return nil, errNoInputProvided
@@ -68,16 +66,11 @@ func config(input model.MeasurementTarget) (*Config, error) {
 			port = "465"
 		}
 	} else {
-		// Check that requested port is a valid integer
-		_, err := strconv.Atoi(parsed.Port())
-		if err != nil {
-			return nil, errInvalidPort
-		} else {
-			port = parsed.Port()
-		}
+		// Valid port is checked by URL parsing
+		port = parsed.Port()
 	}
 
-	valid_config := Config{
+	valid_config := RuntimeConfig{
 		host:       parsed.Hostname(),
 		forced_tls: parsed.Scheme == "smtps",
 		port:       port,
@@ -321,7 +314,6 @@ func (m Measurer) Run(
 	ctx context.Context, sess model.ExperimentSession,
 	measurement *model.Measurement, callbacks model.ExperimentCallbacks,
 ) error {
-
 	log := sess.Logger()
 	trace := measurexlite.NewTrace(0, measurement.MeasurementStartTimeSaved)
 
@@ -372,7 +364,7 @@ func (m Measurer) Run(
 			}
 
 			// Try EHLO + NoOps
-			if !tcp_session.smtp("localhost", 10) {
+			if !tcp_session.smtp("localhost", config.noop_count) {
 				continue
 			}
 		} else {
@@ -386,7 +378,7 @@ func (m Measurer) Run(
 				continue
 			}
 
-			if !tcp_session.smtp("localhost", 10) {
+			if !tcp_session.smtp("localhost", config.noop_count) {
 				continue
 			}
 		}