diff --git a/hub/CHANGELOG.md b/hub/CHANGELOG.md
index ab2be7d0..5b2132ae 100644
--- a/hub/CHANGELOG.md
+++ b/hub/CHANGELOG.md
@@ -1,3 +1,21 @@
+## v0.118.1 — the test mail follows the language too (2026-09-18, R-558)
+
+Found during v0.118.0's own live proof, which is the only reason it was found: I went to press "send
+test notification" for the English demo box and read `sendTestEmail` first.
+
+- **`sendTestEmail` had its own hardcoded Hungarian subject and body** and never went through
+  `FormatCustomerEmail`, so it was the one customer mail v0.118.0 did not localise. It is also **the
+  only customer mail an operator can trigger on demand** — which makes it the one most likely to be
+  used to check whether the localisation works. Left alone, pressing the button for an English
+  household would have answered that question wrongly, and convincingly.
+- Its two sentences are now `mail.test.subject` / `mail.test.body` in the bundle, extracted
+  byte-for-byte from the literals so the Hungarian test mail is unchanged.
+- `TestTestMailFollowsTheHouseholdLanguage`, red-proofed against the hardcoded version ("en test mail
+  subject = \"[Felhom] Teszt értesítés\", want it to contain \"Test notification\"").
+
+**The general form worth keeping: the surface you would use to CHECK a feature is the one most worth
+checking first.** A broken instrument that reports success is worse than a broken feature.
+
 ## v0.118.0 — the household's e-mails follow the household's language (2026-09-18, R-558 / R-555)
 
 **Localisation slice 3, Part A.** The hub has written every customer e-mail in Hungarian whatever the
diff --git a/hub/internal/i18n/locales/en.json b/hub/internal/i18n/locales/en.json
index 63c4c052..321d2a36 100644
--- a/hub/internal/i18n/locales/en.json
+++ b/hub/internal/i18n/locales/en.json
@@ -77,5 +77,7 @@
   "bind.locked.body": "There were too many failed attempts. For safety the link has locked — contact support to link the box.",
   "bind.invalid.lead": "This link is invalid or has expired.",
   "bind.invalid.body": "The link is valid for 7 days. If it has expired, ask support for a new one, or your operator can do the linking.",
-  "bind.htmllang": "en"
+  "bind.htmllang": "en",
+  "mail.test.subject": "[Felhom] Test notification",
+  "mail.test.body": "Dear Customer,\n\nThis is a test notification from the Felhom monitoring system.\nNotifications are working correctly.\n\nBest regards,\nFelhom.eu monitoring"
 }
diff --git a/hub/internal/i18n/locales/hu.json b/hub/internal/i18n/locales/hu.json
index 60cc4d4d..3c36ed79 100644
--- a/hub/internal/i18n/locales/hu.json
+++ b/hub/internal/i18n/locales/hu.json
@@ -77,5 +77,7 @@
   "bind.locked.body": "Túl sok sikertelen próbálkozás történt. Biztonsági okból a hivatkozás zárolódott — kérjük, vedd fel a kapcsolatot az ügyfélszolgálattal a doboz összekötéséhez.",
   "bind.invalid.lead": "Ez a hivatkozás érvénytelen vagy lejárt.",
   "bind.invalid.body": "A hivatkozás 7 napig érvényes. Ha lejárt, kérj újat az ügyfélszolgálattól, vagy az összekötést az üzemeltető is elvégezheti.",
-  "bind.htmllang": "hu"
+  "bind.htmllang": "hu",
+  "mail.test.subject": "[Felhom] Teszt értesítés",
+  "mail.test.body": "Kedves Ügyfél!\n\nEz egy teszt értesítés a Felhom monitoring rendszerből.\nAz értesítések megfelelően működnek.\n\nÜdvözlettel,\nFelhom.eu monitoring"
 }
diff --git a/hub/internal/notify/dispatcher.go b/hub/internal/notify/dispatcher.go
index 9f4e490f..8f2798c4 100644
--- a/hub/internal/notify/dispatcher.go
+++ b/hub/internal/notify/dispatcher.go
@@ -12,6 +12,8 @@ import (
 	"time"
 
 	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
+
+	"gitea.dooplex.hu/admin/felhom-hub/internal/i18n"
 )
 
 // Dispatcher routes events to operator and/or customer email channels.
@@ -199,8 +201,17 @@ func (d *Dispatcher) sendTestEmail(customerID string) {
 	if err != nil || prefs == nil || prefs.Email == "" {
 		d.logger.Printf("[WARN] Test email: no email configured for %s", customerID)
 	} else {
-		subject := "[Felhom] Teszt értesítés"
-		body := "Kedves Ügyfél!\n\nEz egy teszt értesítés a Felhom monitoring rendszerből.\nAz értesítések megfelelően működnek.\n\nÜdvözlettel,\nFelhom.eu monitoring"
+		// The test mail follows the household's language like every other customer mail (R-558).
+		//
+		// It was the ONE that would not have: it is the only customer mail with its own hardcoded
+		// text, because it never goes through FormatCustomerEmail — and it is also the only one an
+		// operator can trigger on demand, so it is the one most likely to be used to CHECK whether
+		// the localisation works. Left alone, pressing "send test" for an English household would
+		// have answered that question wrongly.
+		b := i18n.Shared()
+		lang := d.store.CustomerLanguage(customerID)
+		subject := b.Msg(lang, "mail.test.subject")
+		body := b.Msg(lang, "mail.test.body")
 
 		if err := d.sendEmailFn(prefs.Email, subject, body, nil); err != nil {
 			d.logger.Printf("[ERROR] Test email to %s failed: %v", prefs.Email, err)
diff --git a/hub/internal/notify/language_test.go b/hub/internal/notify/language_test.go
index 20b412a1..5ee9d6d5 100644
--- a/hub/internal/notify/language_test.go
+++ b/hub/internal/notify/language_test.go
@@ -1,10 +1,13 @@
 package notify
 
 import (
+	"io"
+	"log"
 	"strings"
 	"testing"
 
 	"gitea.dooplex.hu/admin/felhom-hub/internal/i18n"
+	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
 )
 
 // Localisation slice 3 (R-558) — the behaviour the bundle exists to produce.
@@ -123,3 +126,44 @@ func TestUnknownLanguageRendersHungarian(t *testing.T) {
 		}
 	}
 }
+
+// The TEST mail follows the household's language too.
+//
+// It is the one customer mail with its own text — it never goes through FormatCustomerEmail — and
+// it is also the only one an operator can trigger on demand, so it is the one most likely to be
+// used to CHECK whether the localisation works. It was still hardcoded Hungarian when the rest of
+// this release was finished; pressing "send test" for an English household would have answered that
+// question wrongly, in the most convincing possible way.
+func TestTestMailFollowsTheHouseholdLanguage(t *testing.T) {
+	for _, tc := range []struct{ lang, want, notWant string }{
+		{"en", "Test notification", "Teszt"},
+		{"hu", "Teszt értesítés", "Test notification"},
+	} {
+		st := newDispStore(t)
+		if err := st.SaveCustomerConfig(&store.CustomerConfig{
+			CustomerID: "c1", APIKey: "k", RetrievalPassword: "p", Language: tc.lang,
+		}); err != nil {
+			t.Fatal(err)
+		}
+		if err := st.SaveNotificationPrefs("c1", "fam@example.com", []string{"test"}, 6); err != nil {
+			t.Fatal(err)
+		}
+		d := NewDispatcher(st, "test-key", "from@felhom.eu", "", false, log.New(io.Discard, "", 0))
+		var subject, body string
+		d.sendEmailFn = func(_, s, b string, _ map[string]string) error {
+			subject, body = s, b
+			return nil
+		}
+		d.ProcessEvent("c1", "test", "info", "", "{}", "hub")
+
+		if !strings.Contains(subject, tc.want) {
+			t.Errorf("%s test mail subject = %q, want it to contain %q", tc.lang, subject, tc.want)
+		}
+		if strings.Contains(subject, tc.notWant) || strings.Contains(body, tc.notWant) {
+			t.Errorf("%s test mail carries the other language (%q):\n%s\n%s", tc.lang, tc.notWant, subject, body)
+		}
+		if body == "" {
+			t.Fatalf("%s test mail has an empty body — the seam did not fire", tc.lang)
+		}
+	}
+}
diff --git a/manifests/hub.yaml b/manifests/hub.yaml
index 10301cf3..978d1505 100644
--- a/manifests/hub.yaml
+++ b/manifests/hub.yaml
@@ -128,7 +128,7 @@ spec:
     spec:
       containers:
         - name: hub
-          image: gitea.dooplex.hu/admin/felhom-hub:0.118.0
+          image: gitea.dooplex.hu/admin/felhom-hub:0.118.1
           ports:
             - containerPort: 8080
               name: http