diff --git a/web/src/App.tsx b/web/src/App.tsx
index d3fd548..dd5f944 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -24,6 +24,7 @@ import { listenForVerification, renewWebPush } from "@/lib/webpushEnable";
 import { plural, t, useLanguageVersion, whenLanguageReady } from "@/lib/i18n";
 import { confirmLeaveUnsaved, hasUnsavedChanges } from "@/lib/unsavedChanges";
 import { BASE_PATH, withBase } from "@/lib/basePath";
+import { DEFAULT_APP_NAME } from "@/lib/brand";
 
 const ContactsView = lazy(() => import("@/views/contacts/ContactsView").then((m) => ({ default: m.ContactsView })));
 const CalendarView = lazy(() => import("@/views/calendar/CalendarView").then((m) => ({ default: m.CalendarView })));
@@ -254,7 +255,7 @@ function AuthedApp() {
     const id = s.roleId("inbox");
     return id ? (s.mailboxes[id]?.unreadEmails ?? 0) : 0;
   });
-  const appName = useSession((s) => s.session?.ihasmail?.appName ?? "ihasmail");
+  const appName = useSession((s) => s.session?.ihasmail?.appName) || DEFAULT_APP_NAME;
   useEffect(() => {
     void import("@/lib/notify").then((m) => {
       m.setBaseTitle(appName);
diff --git a/web/src/lib/__tests__/brand.test.ts b/web/src/lib/__tests__/brand.test.ts
new file mode 100644
index 0000000..90a4f12
--- /dev/null
+++ b/web/src/lib/__tests__/brand.test.ts
@@ -0,0 +1,40 @@
+import { describe, expect, it } from "vitest";
+import { DEFAULT_APP_NAME } from "@/lib/brand";
+
+/*
+ * The name an instance calls itself.
+ *
+ * `APP_NAME` is a runtime variable, so every place showing the name has to ask
+ * the server rather than have it written in. The sign-in page did not (#236's
+ * neighbour): it fetched `/api/config`, received the name and used only
+ * `sourceUrl`, so a rebranded instance still said "ihasmail" on the page a new
+ * user meets first. These pin the shape of the answer rather than the name.
+ */
+
+const nameFrom = (config: { appName?: unknown } | null) =>
+  config && typeof config.appName === "string" && config.appName.trim() ? config.appName.trim() : DEFAULT_APP_NAME;
+
+describe("resolving the instance name", () => {
+  it("uses what the server says", () => {
+    expect(nameFrom({ appName: "Acme Mail" })).toBe("Acme Mail");
+  });
+
+  it("trims it, because a name with an edge of whitespace is a layout bug", () => {
+    expect(nameFrom({ appName: "  Acme Mail  " })).toBe("Acme Mail");
+  });
+
+  it("falls back when the request failed", () => {
+    // A sign-in form with no name on it is worse than one with the wrong name.
+    expect(nameFrom(null)).toBe(DEFAULT_APP_NAME);
+  });
+
+  it("falls back on a name that is empty or only spaces", () => {
+    expect(nameFrom({ appName: "" })).toBe(DEFAULT_APP_NAME);
+    expect(nameFrom({ appName: "   " })).toBe(DEFAULT_APP_NAME);
+  });
+
+  it("falls back on a name that is not a string at all", () => {
+    expect(nameFrom({ appName: 42 })).toBe(DEFAULT_APP_NAME);
+    expect(nameFrom({})).toBe(DEFAULT_APP_NAME);
+  });
+});
diff --git a/web/src/lib/brand.ts b/web/src/lib/brand.ts
new file mode 100644
index 0000000..086a4dc
--- /dev/null
+++ b/web/src/lib/brand.ts
@@ -0,0 +1,13 @@
+/**
+ * What this instance calls itself, when nothing has said otherwise yet.
+ *
+ * `APP_NAME` is a runtime environment variable, so the real answer arrives
+ * from the server -- on `/api/config` before anybody signs in, and on the
+ * session afterwards. This is what stands in until it does, and what stands
+ * for good if the request fails: a sign-in form with no name on it would be
+ * worse than one with the wrong name.
+ *
+ * One constant rather than the string written out at each of them, because
+ * three copies of a default is how two of them end up stale.
+ */
+export const DEFAULT_APP_NAME = "ihasmail";
diff --git a/web/src/views/AppShell.tsx b/web/src/views/AppShell.tsx
index ee809b0..adcd35d 100644
--- a/web/src/views/AppShell.tsx
+++ b/web/src/views/AppShell.tsx
@@ -3,6 +3,7 @@ import { Link, useLocation } from "wouter";
 import { BookOpen, Calendar, ChevronsUpDown, FolderOpen, Globe, HelpCircle, LogOut, Mail, Menu as MenuIcon, Moon, PenSquare, Plus, RefreshCw, Settings, Sun, Upload, Users, X } from "lucide-react";
 import { useSession } from "@/store/session";
 import { withBase } from "@/lib/basePath";
+import { DEFAULT_APP_NAME } from "@/lib/brand";
 import { useEffectiveTheme, useSettings } from "@/store/settings";
 import { toggleTarget } from "@/lib/palette";
 import { useMail } from "@/store/mail";
@@ -37,6 +38,7 @@ export function AppShell({ children }: { children: ReactNode }) {
   const pushState = useSession((s) => s.pushState);
   const session = useSession((s) => s.session);
   const logout = useSession((s) => s.logout);
+  const appName = useSession((s) => s.session?.ihasmail?.appName) || DEFAULT_APP_NAME;
   const acctMenu = useMenu();
   /*
    * "Go to folder" (#233), hosted here rather than in the mail view because
@@ -90,10 +92,12 @@ export function AppShell({ children }: { children: ReactNode }) {
         </button>
         <Link href="/mail" className="brand">
           <img src={withBase("/img/logo.png")} alt="" />
-          {/* A product name, not a word. "ihasmail" translated is a different
-              product, and the one on the tab beside it is still called this. */}
+          {/* A product name, not a word: translated it is a different product.
+              Read from the session rather than written here, so a deployment
+              that set APP_NAME is called what it calls itself -- the document
+              title has taken it from there all along. */}
           <span className="brand-name notranslate" translate="no">
-            ihasmail
+            {appName}
           </span>
         </Link>
         <SearchBar />
diff --git a/web/src/views/Login.tsx b/web/src/views/Login.tsx
index b152937..2bb64a0 100644
--- a/web/src/views/Login.tsx
+++ b/web/src/views/Login.tsx
@@ -5,6 +5,7 @@ import { ApiError } from "@/jmap/client";
 import { withBase } from "@/lib/basePath";
 import { DEFAULT_SOURCE_URL } from "@/lib/source";
 import { APP_VERSION } from "@/lib/version";
+import { DEFAULT_APP_NAME } from "@/lib/brand";
 import { t } from "@/lib/i18n";
 
 export function LoginPage() {
@@ -13,11 +14,28 @@ export function LoginPage() {
   // network, and that includes whoever is looking at this form. The server says
   // where its own source lives, so a modified deployment points at its own.
   const [sourceUrl, setSourceUrl] = useState(DEFAULT_SOURCE_URL);
+  /*
+   * What this instance calls itself.
+   *
+   * The name was in the `/api/config` answer all along and only `sourceUrl`
+   * was taken out of it, so an instance with `APP_NAME` set still said
+   * "ihasmail" on the one page a new user meets first -- the page where the
+   * name matters most, and the one the rebranding guide had to tell people to
+   * patch themselves.
+   *
+   * Defaults to ihasmail and stays there if the request fails, because a
+   * sign-in form with no name on it would be worse than a wrong one.
+   */
+  const [appName, setAppName] = useState(DEFAULT_APP_NAME);
   useEffect(() => {
     let live = true;
     fetch(withBase("/api/config"))
       .then((r) => (r.ok ? r.json() : null))
-      .then((c) => { if (live && c?.sourceUrl) setSourceUrl(c.sourceUrl as string); })
+      .then((c) => {
+        if (!live || !c) return;
+        if (c.sourceUrl) setSourceUrl(c.sourceUrl as string);
+        if (typeof c.appName === "string" && c.appName.trim()) setAppName(c.appName.trim());
+      })
       .catch(() => { /* the default stands */ });
     return () => { live = false; };
   }, []);
@@ -55,7 +73,9 @@ export function LoginPage() {
       <form className="login-card" onSubmit={submit}>
         <div className="logo">
           <img src={withBase("/img/logo.png")} alt="" width={120} height={143} />
-          <h1 className="notranslate" translate="no">ihasmail</h1>
+          {/* A product name, not a word: not translated, and not guessed at
+              from the page it is on. */}
+          <h1 className="notranslate" translate="no">{appName}</h1>
           <p className="tagline">{t("Fast, friendly webmail. Your mailbox, your way.")}</p>
         </div>
         {error && (