diff --git a/internal/engine/experiment/smtp/smtp.go b/internal/engine/experiment/smtp/smtp.go
index a0d38ac..09d3484 100644
--- a/internal/engine/experiment/smtp/smtp.go
+++ b/internal/engine/experiment/smtp/smtp.go
@@ -133,12 +133,8 @@ type SMTPRunner struct {
 
 func (r SMTPRunner) smtp_error(err error) {
 	key := net.JoinHostPort(r.addr, r.port)
-	errors, exists := r.tk.SMTPErrors[key]
-	if exists {
-		r.tk.SMTPErrors[key] = append(errors, tracex.NewFailure(err))
-	} else {
-		r.tk.SMTPErrors[key] = []*string{tracex.NewFailure(err)}
-	}
+	// Key is initialized in conn() no need to check here
+	r.tk.SMTPErrors[key] = append(r.tk.SMTPErrors[key], tracex.NewFailure(err))
 }
 
 func (r SMTPRunner) resolve(host string) ([]string, bool) {
@@ -156,7 +152,13 @@ func (r SMTPRunner) resolve(host string) ([]string, bool) {
 }
 
 func (r SMTPRunner) conn(addr string) (net.Conn, bool) {
+	// Initialize addr field and corresponding errors in TestKeys
 	r.addr = addr
+	if r.tk.SMTPErrors == nil {
+		r.tk.SMTPErrors = make(map[string][]*string)
+	}
+	r.tk.SMTPErrors[net.JoinHostPort(addr, r.port)] = []*string{}
+
 	dialer := r.trace.NewDialerWithoutResolver(r.logger)
 	conn, err := dialer.DialContext(r.ctx, "tcp", net.JoinHostPort(r.addr, r.port))
 	r.tk.TCPConnect = append(r.tk.TCPConnect, r.trace.TCPConnects()...)
@@ -243,8 +245,6 @@ func (m Measurer) Run(
 	}
 
 	tk := new(TestKeys)
-	// TODO: make it so we don't forget it
-	tk.SMTPErrors = make(map[string][]*string)
 	measurement.TestKeys = tk
 
 	ctx, cancel := context.WithTimeout(ctx, 60*time.Second)