fixes

internal/otpdelivery/smtp/sender_test.go

@@ -29,3 +29,30 @@ func TestHumanTTLRoundsNetworkSkew(t *testing.T) {
 		t.Fatalf("humanTTL = %q", got)
 	}
 }
+
+// TestEmailContentUsesConfiguredAppName asserts the login-code email is
+// branded with the operator's configured product name, not the package's
+// internal "telesrv" fallback — the subject/body previously always said
+// "Your telesrv login code" regardless of Config.AppName.
+func TestEmailContentUsesConfiguredAppName(t *testing.T) {
+	subject, body := emailContent("OwpenGram", "12345", 5*time.Minute)
+	if subject != "Your OwpenGram login code" {
+		t.Fatalf("subject = %q, want %q", subject, "Your OwpenGram login code")
+	}
+	if !strings.Contains(body, "Your OwpenGram login code is 12345.") {
+		t.Fatalf("body missing branded code line: %q", body)
+	}
+	if strings.Contains(subject, "telesrv") || strings.Contains(body, "telesrv") {
+		t.Fatalf("email still mentions telesrv instead of the configured app name:\nsubject=%q\nbody=%q", subject, body)
+	}
+}
+
+// TestNewDefaultsAppNameToTelesrvWhenUnset asserts the package's own
+// self-contained fallback (used only if a caller forgets to pass AppName)
+// still works, mirroring FromName/TLSMode/Timeout's existing defaulting.
+func TestNewDefaultsAppNameToTelesrvWhenUnset(t *testing.T) {
+	sender := New(Config{Host: "smtp.example.test", Port: 25, From: "noreply@example.test"})
+	if sender.cfg.AppName != "telesrv" {
+		t.Fatalf("cfg.AppName = %q, want default %q", sender.cfg.AppName, "telesrv")
+	}
+}