diff --git a/src/pages/LoginPage.tsx b/src/pages/LoginPage.tsx
index 56c891e..24f4182 100644
--- a/src/pages/LoginPage.tsx
+++ b/src/pages/LoginPage.tsx
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
  */
 
-import { type FormEvent, useState } from 'react';
+import { useCallback, useEffect, useRef, useState } from 'react';
 import { useLocation } from 'react-router-dom';
 import { useTranslation } from 'react-i18next';
 import { ArrowRight, Loader2 } from 'lucide-react';
@@ -12,35 +12,42 @@ import { ArrowRight, Loader2 } from 'lucide-react';
 import Logo from '@/components/common/Logo';
 import { useDocumentTitle } from '@/hooks/useDocumentTitle';
 import { Button } from '@/components/ui/button';
-import { Input } from '@/components/ui/input';
 import { Card, CardContent, CardHeader } from '@/components/ui/card';
 import { startAuthFlow } from '@/services/auth/oauth';
 
+/**
+ * INBUXA: straight to the server's own sign-in page, which asks for the
+ * username and password. There is no account-name step first: INBUXA Admin
+ * talks to one known server, so there is nothing to look up per account (see
+ * `discover`). The card stays only for when getting there fails.
+ */
 export default function LoginPage() {
   const { t } = useTranslation();
   const location = useLocation();
   const originalPath = (location.state as { from?: string } | null)?.from ?? null;
-  const [username, setUsername] = useState('');
   const [error, setError] = useState<string | null>(null);
-  const [loading, setLoading] = useState(false);
+  const [loading, setLoading] = useState(true);
+  const started = useRef(false);
 
   useDocumentTitle(t('login.title', 'Sign in'));
 
-  async function handleSubmit(e: FormEvent) {
-    e.preventDefault();
-    const trimmed = username.trim();
-    if (!trimmed) return;
-
+  const go = useCallback(async () => {
     setError(null);
     setLoading(true);
-
     try {
-      await startAuthFlow(trimmed, originalPath);
+      await startAuthFlow(null, originalPath);
     } catch (err) {
       setError(err instanceof Error ? err.message : t('login.error', 'An unexpected error occurred'));
       setLoading(false);
     }
-  }
+  }, [originalPath, t]);
+
+  useEffect(() => {
+    // Once, even under StrictMode's double effect.
+    if (started.current) return;
+    started.current = true;
+    void go();
+  }, [go]);
 
   return (
     <div className="flex min-h-screen items-center justify-center bg-content-background px-4">
@@ -49,42 +56,22 @@ export default function LoginPage() {
           <Logo />
         </CardHeader>
 
-        <CardContent>
-          <form onSubmit={handleSubmit} className="space-y-4">
-            <div className="space-y-2">
-              <p className="text-center text-sm text-muted-foreground">
-                {t('login.prompt', 'Enter your account name to continue')}
-              </p>
-              <Input
-                id="username"
-                type="text"
-                autoComplete="username"
-                autoFocus
-                placeholder={t('login.usernamePlaceholder', 'user@example.com')}
-                value={username}
-                onChange={(e) => setUsername(e.target.value)}
-                disabled={loading}
-                aria-label={t('login.prompt', 'Enter your account name to continue')}
-              />
-            </div>
-
-            {error && (
-              <p className="text-sm text-destructive" role="alert">
-                {error}
-              </p>
+        <CardContent className="space-y-4">
+          {error && (
+            <p className="text-sm text-destructive" role="alert">
+              {error}
+            </p>
+          )}
+          <Button type="button" className="w-full" disabled={loading} onClick={() => void go()}>
+            {loading ? (
+              <Loader2 className="animate-spin" />
+            ) : (
+              <>
+                {t('login.continue', 'Continue')}
+                <ArrowRight />
+              </>
             )}
-
-            <Button type="submit" className="w-full" disabled={loading || !username.trim()}>
-              {loading ? (
-                <Loader2 className="animate-spin" />
-              ) : (
-                <>
-                  {t('login.continue', 'Continue')}
-                  <ArrowRight />
-                </>
-              )}
-            </Button>
-          </form>
+          </Button>
         </CardContent>
       </Card>
     </div>
diff --git a/src/services/auth/oauth.test.ts b/src/services/auth/oauth.test.ts
index cfc4fd6..1563435 100644
--- a/src/services/auth/oauth.test.ts
+++ b/src/services/auth/oauth.test.ts
@@ -102,3 +102,50 @@ describe('generateCodeChallenge', () => {
     }
   });
 });
+
+describe('startAuthFlow (INBUXA: no account-name step)', () => {
+  const metadata = {
+    authorization_endpoint: '/login',
+    token_endpoint: '/auth/token',
+    scopes_supported: ['openid', 'offline_access'],
+  };
+
+  async function run(username: string | null) {
+    document.head.innerHTML = '<meta name="api-base-url" content="https://mail.example.org" />';
+    const requested: string[] = [];
+    const fetchMock = async (url: string) => {
+      requested.push(url);
+      return new Response(JSON.stringify(metadata), { status: 200 });
+    };
+    const originalFetch = globalThis.fetch;
+    globalThis.fetch = fetchMock as typeof fetch;
+    let href = '';
+    const originalLocation = window.location;
+    Object.defineProperty(window, 'location', {
+      configurable: true,
+      value: { ...originalLocation, origin: 'https://admin.example.org', pathname: '/', search: '', set href(v: string) { href = v; }, get href() { return href; } },
+    });
+    try {
+      const { startAuthFlow } = await import('./oauth');
+      await startAuthFlow(username);
+    } finally {
+      globalThis.fetch = originalFetch;
+      Object.defineProperty(window, 'location', { configurable: true, value: originalLocation });
+    }
+    return { requested, target: new URL(href) };
+  }
+
+  it('reads the server-wide configuration and goes straight to its sign-in page', async () => {
+    const { requested, target } = await run(null);
+    expect(requested).toEqual(['https://mail.example.org/.well-known/openid-configuration']);
+    expect(`${target.origin}${target.pathname}`).toBe('https://mail.example.org/login');
+    expect(target.searchParams.has('login_hint')).toBe(false);
+    expect(target.searchParams.get('redirect_uri')).toBe('https://admin.example.org/oauth/callback');
+  });
+
+  it('still looks an account up, and passes the hint, when given one', async () => {
+    const { requested, target } = await run('someone@example.org');
+    expect(requested).toEqual(['https://mail.example.org/api/discover/someone%40example.org']);
+    expect(target.searchParams.get('login_hint')).toBe('someone@example.org');
+  });
+});
diff --git a/src/services/auth/oauth.ts b/src/services/auth/oauth.ts
index 5c30b72..67f9fa2 100644
--- a/src/services/auth/oauth.ts
+++ b/src/services/auth/oauth.ts
@@ -20,13 +20,24 @@ interface DiscoveryResponse {
   scopes_supported?: string[];
 }
 
-export async function discover(username: string): Promise<DiscoveryResponse> {
-  const url = `${getApiBaseUrl()}/api/discover/${encodeURIComponent(username)}`;
+/**
+ * The server's OAuth endpoints.
+ *
+ * Upstream asks for the account name first and looks the endpoints up per
+ * account, because a domain there can sign in at its own identity provider.
+ * INBUXA Admin talks to one known server whose own sign-in page handles every
+ * account, so it reads the server's published OpenID configuration instead,
+ * which needs no account name. Given one, it still asks per account.
+ */
+export async function discover(username?: string | null): Promise<DiscoveryResponse> {
+  const url = username
+    ? `${getApiBaseUrl()}/api/discover/${encodeURIComponent(username)}`
+    : `${getApiBaseUrl()}/.well-known/openid-configuration`;
   const response = await fetch(url);
   if (!response.ok) {
     throw new Error(
       i18n.t('oauth.discoveryFailed', 'Discovery failed for "{{username}}": {{status}} {{statusText}}', {
-        username,
+        username: username ?? getApiBaseUrl(),
         status: response.status,
         statusText: response.statusText,
       }),
@@ -136,7 +147,7 @@ function getRedirectUri(): string {
   return `${window.location.origin}${basePath}/oauth/callback`;
 }
 
-export async function startAuthFlow(username: string, returnUrl?: string | null): Promise<void> {
+export async function startAuthFlow(username: string | null, returnUrl?: string | null): Promise<void> {
   const { authorization_endpoint, token_endpoint, end_session_endpoint, scopes_supported } = await discover(username);
 
   const codeVerifier = generateCodeVerifier();
@@ -170,9 +181,11 @@ export async function startAuthFlow(username: string, returnUrl?: string | null)
     code_challenge: codeChallenge,
     code_challenge_method: codeChallengeMethod,
     state,
-    login_hint: username,
     prompt: 'login',
   });
+  if (username) {
+    params.set('login_hint', username);
+  }
 
   let scope: string;
   if (SCOPES && SCOPES.length > 0) {