diff --git a/apxtri/models/Notifications.js b/apxtri/models/Notifications.js
index 3b5f523..7846a1b 100644
--- a/apxtri/models/Notifications.js
+++ b/apxtri/models/Notifications.js
@@ -262,6 +262,98 @@ Notifications.filternoitif = (tribe, tpl, alias, channel = "push", topics = [])
   return ok;
 };
 
+/**
+ * Language of a recipient: the language of its own app (persons.lg, stamped by
+ * Persons.managetopic on each topic subscription) wins over the language of
+ * whoever triggered the event, which is only a fallback. Anything outside
+ * fr/en is forced to "en", the same way checkHeaders forces xlang.
+ */
+Notifications.recipientlang = (person, fallback) =>
+  person && ["fr", "en"].includes(person.lg)
+    ? person.lg
+    : ["fr", "en"].includes(fallback)
+      ? fallback
+      : "en";
+
+const ISO_DATE_RE = /^\d{4}-\d{2}-\d{2}/;
+const localdate_re = /\{\{#localdate\}\}\s*([^\s}]+)\s*\{\{\/localdate\}\}/g;
+
+/**
+ * A date is never formatted by the caller: it sends the raw value (ISO) and the
+ * template declares how to display it.
+ *
+ *   seekertemplate_fr.js : tpl.dateformat = { bookdate: "DD/MM/YYYY" }
+ *   template             : ... le {{#localdate}}bookdate{{/localdate}} ...
+ *
+ * The text of the section is the NAME of the field to display, and it is not
+ * "{{bookdate}}": mustache hands the raw inner text of a lambda, it does not
+ * render it, so the value is read in the view (closure) and not through a
+ * render callback. tpl.dateformat gives the dayjs format of that field.
+ *
+ * Anything that is not an ISO date (missing, empty, ...) is returned untouched,
+ * which also prevents an "Invalid Date" from reaching a recipient.
+ *
+ * The value MUST be a factory (() => function (text)): mustache calls a function
+ * found in the data with no argument during the lookup
+ * (mustache.js Context.lookup), so a plain (text) => ... lambda is silently
+ * ignored and the section renders its own content.
+ */
+Notifications.localdate = (tpl, view) => () => (text) => {
+  const field = text.trim();
+  const raw = view ? view[field] : undefined;
+  const value = raw === undefined || raw === null ? "" : String(raw).trim();
+  const fmt = (tpl.dateformat || {})[field];
+  if (!fmt || !ISO_DATE_RE.test(value)) return value;
+  return dayjs(value).format(fmt);
+};
+
+/**
+ * Single rendering point for every notification template (email subject/html/
+ * text and push notiftitle/notifdescription).
+ *
+ *   Notifications.render(tpl, view, ["subject", "html", "text"])
+ *
+ * `keys` is explicit on purpose: a template without tpl.text must keep failing
+ * instead of silently producing a mail without its text part. `meta` is only
+ * used to make the warnings actionable ({ template, lg }).
+ *
+ * Warns on both directions of a mismatch between tpl.dateformat and the
+ * template: a declared format never used means the raw ISO date is displayed,
+ * and a {{#localdate}} without declaration means the same thing silently.
+ */
+Notifications.render = (tpl, view, keys, meta = {}) => {
+  view.localdate = Notifications.localdate(tpl, view);
+  const rendered = {};
+  try {
+    for (const k of keys) rendered[k] = Mustache.render(tpl[k], view);
+  } finally {
+    // view is the caller object (req.body, emailsto entry, push recipient) and
+    // is persisted as is in persons.notifications[]: do not leak the factory.
+    delete view.localdate;
+  }
+  const sources = ["subject", "html", "text", "notiftitle", "notifdescription"]
+    .map((k) => (typeof tpl[k] === "string" ? tpl[k] : ""))
+    .join("\n");
+  const used = new Set([...sources.matchAll(localdate_re)].map((m) => m[1]));
+  const declared = Object.keys(tpl.dateformat || {});
+  const where = `${meta.template || "?"}_${meta.lg || "?"}`;
+  for (const field of declared) {
+    if (!used.has(field))
+      console.warn(
+        currentmod,
+        `dateformat "${field}" declared but never used in ${where}`
+      );
+  }
+  for (const field of used) {
+    if (!declared.includes(field))
+      console.warn(
+        currentmod,
+        `{{#localdate}}${field}} used without dateformat in ${where}, raw value displayed`
+      );
+  }
+  return rendered;
+};
+
 Notifications.manageemail = async (
   data,
   templatename,
@@ -360,9 +452,13 @@ Notifications.manageemail = async (
       emailtosend.to = emailtosend.to.slice(0, -1);
       emailtosend.templatename = templatename;
       emailtosend.lg = lg;
-      emailtosend.subject = Mustache.render(tplemail.subject, email);
-      emailtosend.html = Mustache.render(tplemail.html, email);
-      emailtosend.text = Mustache.render(tplemail.text, email);
+      Object.assign(
+        emailtosend,
+        Notifications.render(tplemail, email, ["subject", "html", "text"], {
+          template: templatename,
+          lg,
+        })
+      );
       if (email.cc) {
         emailtosend.cc += emailtosend.cc && emailtosend.cc != "" ? "," : "";
         emailtosend.cc += email.cc.join(",");
diff --git a/apxtri/models/Pagans.js b/apxtri/models/Pagans.js
index 7d39403..4f1e5b3 100644
--- a/apxtri/models/Pagans.js
+++ b/apxtri/models/Pagans.js
@@ -264,9 +264,10 @@ Pagans.sendmailkey = (data) => {
   const maildata = {
     from: tplemail.sender,
     to: person.email,
-    subject: Mustache.render(tplemail.subject, person),
-    html: Mustache.render(tplemail.html, person),
-    text: Mustache.render(tplemail.text, person),
+    ...Notifications.render(tplemail, person, ["subject", "html", "text"], {
+      template: "createidentity",
+      lg: data.lg,
+    }),
     attachments: [
       {
         filename: `${person.alias}_privatekey.txt`,
diff --git a/apxtri/models/PagansPeter.js b/apxtri/models/PagansPeter.js
index 7f6b2ed..836f1e3 100644
--- a/apxtri/models/PagansPeter.js
+++ b/apxtri/models/PagansPeter.js
@@ -165,9 +165,10 @@ Pagans.sendmailkey = (data) => {
   const maildata = {
     from: tplemail.sender,
     to: person.email,
-    subject: Mustache.render(tplemail.subject, person),
-    html: Mustache.render(tplemail.html, person),
-    text: Mustache.render(tplemail.text, person),
+    ...Notifications.render(tplemail, person, ["subject", "html", "text"], {
+      template: "createidentity",
+      lg: data.lg,
+    }),
     attachments: [
       {
         filename: `${person.alias}_privatekey.txt`,
diff --git a/apxtri/routes/notifications.js b/apxtri/routes/notifications.js
index a6c58a1..fdf82c1 100644
--- a/apxtri/routes/notifications.js
+++ b/apxtri/routes/notifications.js
@@ -284,7 +284,7 @@ router.get("/checkemail/:email/:digit6", checkHeaders, async (req, res) => {
       },
       "checkemail",
       "adminapi",
-      req.session.header.xlang || "fr",
+      Notifications.recipientlang(null, req.session.header.xlang),
       1,
       ["anonymous"]
     );