diff --git a/server/config/appName.js b/server/config/appName.js
new file mode 100644
index 0000000..11a33dd
--- /dev/null
+++ b/server/config/appName.js
@@ -0,0 +1,20 @@
+import { getDb } from './database.js';
+
+/**
+ * Resolve the configured application name.
+ * Resolution order: admin-set 'app_name' setting → APP_NAME env var → 'Redlight'.
+ *
+ * The app name is stored in the settings table under the key 'app_name'
+ * (see routes/branding.js). This helper is the single source of truth so the
+ * configured name is used consistently across emails, the 2FA issuer, etc.
+ */
+export async function getAppName() {
+  try {
+    const db = getDb();
+    const row = await db.get("SELECT value FROM settings WHERE key = 'app_name'");
+    if (row?.value) return row.value;
+  } catch {
+    // fall through to env/default if the DB is unavailable
+  }
+  return process.env.APP_NAME || 'Redlight';
+}
diff --git a/server/config/bbb.js b/server/config/bbb.js
index 0b84c46..80b1850 100644
--- a/server/config/bbb.js
+++ b/server/config/bbb.js
@@ -1,6 +1,7 @@
 import crypto from 'crypto';
 import xml2js from 'xml2js';
 import { log, fmtDuration, fmtStatus, fmtMethod, fmtReturncode, sanitizeBBBParams } from './logger.js';
+import { t } from './emaili18n.js';
 
 const BBB_URL = process.env.BBB_URL || 'https://your-bbb-server.com/bigbluebutton/api/';
 const BBB_SECRET = process.env.BBB_SECRET || '';
@@ -73,15 +74,15 @@ function getRoomPasswords(uid) {
   return { moderatorPW: modPw, attendeePW: attPw };
 }
 
-export async function createMeeting(room, logoutURL, loginURL = null, presentationUrl = null, analyticsCallbackURL = null) {
+export async function createMeeting(room, logoutURL, loginURL = null, presentationUrl = null, analyticsCallbackURL = null, lang = 'en') {
   const { moderatorPW, attendeePW } = getRoomPasswords(room.uid);
 
   // Build welcome message with guest invite link
   // HTML-escape user-controlled content to prevent stored XSS via BBB
-  let welcome = room.welcome_message ? escapeHtml(room.welcome_message) : t('defaultWelcome');
+  let welcome = room.welcome_message ? escapeHtml(room.welcome_message) : escapeHtml(t(lang, 'bbb.defaultWelcome'));
   if (logoutURL) {
     const guestLink = `${logoutURL}/join/${room.uid}`;
-    welcome += `<br><br>To invite other participants, share this link:<br><a href="${escapeHtml(guestLink)}">${escapeHtml(guestLink)}</a>`;
+    welcome += `<br><br>${escapeHtml(t(lang, 'bbb.inviteHint'))}<br><a href="${escapeHtml(guestLink)}">${escapeHtml(guestLink)}</a>`;
     // Access code is intentionally NOT shown in the welcome message to prevent
     // leaking it to all meeting participants.
   }
diff --git a/server/config/mailer.js b/server/config/mailer.js
index 236aba9..1296df4 100644
--- a/server/config/mailer.js
+++ b/server/config/mailer.js
@@ -64,7 +64,6 @@ export async function sendVerificationEmail(to, name, verifyUrl, appName = 'Redl
   const from = process.env.SMTP_FROM || process.env.SMTP_USER;
   const headerAppName = sanitizeHeaderValue(appName);
   const safeName = escapeHtml(name);
-  const safeAppName = escapeHtml(appName);
 
   await transporter.sendMail({
     from: `"${headerAppName}" <${from}>`,
@@ -112,7 +111,6 @@ export async function sendFederationInviteEmail(to, name, fromUser, roomName, me
   const safeFromUser = escapeHtml(fromUser);
   const safeRoomName = escapeHtml(roomName);
   const safeMessage = message ? escapeHtml(message) : null;
-  const safeAppName = escapeHtml(appName);
 
   const introHtml = t(lang, 'email.federationInvite.intro')
     .replace('{fromUser}', `<strong style="color:#cdd6f4;">${safeFromUser}</strong>`);
diff --git a/server/i18n/de.json b/server/i18n/de.json
index e62485e..b1b2401 100644
--- a/server/i18n/de.json
+++ b/server/i18n/de.json
@@ -42,5 +42,9 @@
       "note": "Der Termin wurde automatisch aus deinem Kalender entfernt.",
       "footer": "Diese Nachricht wurde automatisch von {appName} versendet."
     }
+  },
+  "bbb": {
+    "defaultWelcome": "Willkommen im Meeting!",
+    "inviteHint": "Lade weitere Teilnehmer ein, indem du diesen Link teilst:"
   }
 }
diff --git a/server/i18n/en.json b/server/i18n/en.json
index e36856e..ddbcaa1 100644
--- a/server/i18n/en.json
+++ b/server/i18n/en.json
@@ -42,5 +42,9 @@
       "note": "The event has been automatically removed from your calendar.",
       "footer": "This message was sent automatically by {appName}."
     }
+  },
+  "bbb": {
+    "defaultWelcome": "Welcome to the meeting!",
+    "inviteHint": "To invite other participants, share this link:"
   }
 }
diff --git a/server/index.js b/server/index.js
index 7505fa6..3087e4b 100644
--- a/server/index.js
+++ b/server/index.js
@@ -51,7 +51,14 @@ const corsOptions = process.env.APP_URL
   ? { origin: process.env.APP_URL, credentials: true }
   : { origin: false };
 app.use(cors(corsOptions));
-app.use(express.json({ limit: '100kb' }));
+// Global JSON body limit kept tight as a hardening measure. The BBB learning
+// analytics callback can send much larger payloads, so it is excluded here and
+// gets its own, more generous limit on the route itself (see routes/analytics.js).
+const jsonParser = express.json({ limit: '100kb' });
+app.use((req, res, next) => {
+  if (req.path.startsWith('/api/analytics/callback/')) return next();
+  return jsonParser(req, res, next);
+});
 // Request/Response logging (filters sensitive fields)
 app.use(requestResponseLogger);
 
diff --git a/server/routes/admin.js b/server/routes/admin.js
index 431a786..5602a4d 100644
--- a/server/routes/admin.js
+++ b/server/routes/admin.js
@@ -4,6 +4,7 @@ import { v4 as uuidv4 } from 'uuid';
 import { getDb } from '../config/database.js';
 import { authenticateToken, requireAdmin, getBaseUrl } from '../middleware/auth.js';
 import { isMailerConfigured, sendInviteEmail } from '../config/mailer.js';
+import { getAppName } from '../config/appName.js';
 import { log } from '../config/logger.js';
 import {
   getOAuthConfig,
@@ -217,9 +218,8 @@ router.post('/invites', authenticateToken, requireAdmin, async (req, res) => {
     const baseUrl = getBaseUrl(req);
     const inviteUrl = `${baseUrl}/register?invite=${token}`;
 
-    // Load app name
-    const brandingSetting = await db.get("SELECT value FROM settings WHERE key = 'app_name'");
-    const appName = brandingSetting?.value || 'Redlight';
+    // Load configured app name (admin setting → env → default)
+    const appName = await getAppName();
 
     if (isMailerConfigured()) {
       try {
diff --git a/server/routes/analytics.js b/server/routes/analytics.js
index 0a3f6b2..5f4c367 100644
--- a/server/routes/analytics.js
+++ b/server/routes/analytics.js
@@ -1,4 +1,4 @@
-import { Router } from 'express';
+import { Router, json } from 'express';
 import crypto from 'crypto';
 import ExcelJS from 'exceljs';
 import PDFDocument from 'pdfkit';
@@ -10,7 +10,9 @@ import { getAnalyticsToken } from '../config/bbb.js';
 const router = Router();
 
 // POST /api/analytics/callback/:uid?token=... - BBB Learning Analytics callback (token-secured)
-router.post('/callback/:uid', async (req, res) => {
+// Excluded from the global 100kb body limit (see index.js): learning analytics
+// payloads for large meetings can be several MB.
+router.post('/callback/:uid', json({ limit: '5mb' }), async (req, res) => {
   try {
     const { token } = req.query;
     const expectedToken = getAnalyticsToken(req.params.uid);
diff --git a/server/routes/auth.js b/server/routes/auth.js
index 09f18a2..4e65b86 100644
--- a/server/routes/auth.js
+++ b/server/routes/auth.js
@@ -13,6 +13,7 @@ import redis from '../config/redis.js';
 import { authenticateToken, generateToken, getBaseUrl } from '../middleware/auth.js';
 import { isMailerConfigured, sendVerificationEmail } from '../config/mailer.js';
 import { getOAuthConfig, discoverOIDC } from '../config/oauth.js';
+import { getAppName } from '../config/appName.js';
 import { log } from '../config/logger.js';
 
 if (!process.env.JWT_SECRET) {
@@ -179,7 +180,8 @@ router.post('/register', registerLimiter, async (req, res) => {
       return res.status(400).json({ error: `Password must not exceed ${MAX_PASSWORD_LENGTH} characters` });
     }
 
-    const existing = await db.get('SELECT id FROM users WHERE email = ?', [email]);
+    // Emails are stored lowercased, so compare lowercased to catch case-variant duplicates
+    const existing = await db.get('SELECT id FROM users WHERE email = ?', [email.toLowerCase()]);
     if (existing) {
       return res.status(409).json({ error: 'Email is already in use' });
     }
@@ -213,12 +215,8 @@ router.post('/register', registerLimiter, async (req, res) => {
       const baseUrl = getBaseUrl(req);
       const verifyUrl = `${baseUrl}/verify-email?token=${verificationToken}`;
 
-      // Load app name from branding settings
-      const brandingSetting = await db.get("SELECT value FROM settings WHERE key = 'branding'");
-      let appName = 'Redlight';
-      if (brandingSetting?.value) {
-        try { appName = JSON.parse(brandingSetting.value).appName || appName; } catch {}
-      }
+      // Load configured app name (admin setting → env → default)
+      const appName = await getAppName();
 
       try {
         await sendVerificationEmail(email.toLowerCase(), display_name, verifyUrl, appName, 'en');
@@ -327,11 +325,7 @@ router.post('/resend-verification', resendVerificationLimiter, async (req, res)
     const baseUrl = getBaseUrl(req);
     const verifyUrl = `${baseUrl}/verify-email?token=${verificationToken}`;
 
-    const brandingSetting = await db.get("SELECT value FROM settings WHERE key = 'branding'");
-    let appName = 'Redlight';
-    if (brandingSetting?.value) {
-      try { appName = JSON.parse(brandingSetting.value).appName || appName; } catch {}
-    }
+    const appName = await getAppName();
 
     try {
       await sendVerificationEmail(email.toLowerCase(), user.display_name || user.name, verifyUrl, appName, user.language || 'en');
@@ -774,12 +768,8 @@ router.post('/2fa/setup', authenticateToken, twoFaLimiter, async (req, res) => {
 
     const secret = new OTPAuth.Secret({ size: 20 });
 
-    // Load app name from branding settings
-    const brandingSetting = await db.get("SELECT value FROM settings WHERE key = 'branding'");
-    let issuer = 'Redlight';
-    if (brandingSetting?.value) {
-      try { issuer = JSON.parse(brandingSetting.value).appName || issuer; } catch {}
-    }
+    // Use the configured app name as the TOTP issuer (admin setting → env → default)
+    const issuer = await getAppName();
 
     const totp = new OTPAuth.TOTP({
       issuer,
diff --git a/server/routes/calendar.js b/server/routes/calendar.js
index f7fc946..6b37179 100644
--- a/server/routes/calendar.js
+++ b/server/routes/calendar.js
@@ -4,6 +4,7 @@ import { getDb } from '../config/database.js';
 import { authenticateToken, getBaseUrl } from '../middleware/auth.js';
 import { log } from '../config/logger.js';
 import { sendCalendarInviteEmail } from '../config/mailer.js';
+import { getAppName } from '../config/appName.js';
 import {
   isFederationEnabled,
   getFederationDomain,
@@ -219,7 +220,7 @@ router.put('/events/:id', authenticateToken, async (req, res) => {
         end_time = COALESCE(?, end_time),
         room_uid = ?,
         color = COALESCE(?, color),
-        reminder_minutes = COALESCE(?, reminder_minutes),
+        reminder_minutes = ?,
         reminder_sent_at = ${resetReminder ? 'NULL' : 'reminder_sent_at'},
         updated_at = CURRENT_TIMESTAMP
       WHERE id = ?
@@ -230,7 +231,9 @@ router.put('/events/:id', authenticateToken, async (req, res) => {
       end_time || null,
       room_uid !== undefined ? (room_uid || null) : event.room_uid,
       color || null,
-      validReminder !== undefined ? validReminder : null,
+      // Not in payload → keep existing; present (incl. null) → set/clear directly.
+      // COALESCE can't be used here: it would treat an explicit null as "keep".
+      validReminder !== undefined ? validReminder : event.reminder_minutes,
       req.params.id,
     ]);
 
@@ -323,7 +326,7 @@ router.post('/events/:id/share', authenticateToken, async (req, res) => {
     if (targetUser?.email) {
       const appUrl = getBaseUrl(req);
       const inboxUrl = `${appUrl}/federation/inbox`;
-      const appName = process.env.APP_NAME || 'Redlight';
+      const appName = await getAppName();
       const senderUser = await db.get('SELECT name, display_name FROM users WHERE id = ?', [req.user.id]);
       const fromDisplay = (senderUser?.display_name && senderUser.display_name !== '') ? senderUser.display_name : (senderUser?.name || req.user.name);
       sendCalendarInviteEmail(
@@ -645,7 +648,7 @@ router.post(['/receive-event', '/calendar-event'], calendarFederationLimiter, as
     if (targetUser.email) {
       const appUrl = getBaseUrl(req);
       const inboxUrl = `${appUrl}/federation/inbox`;
-      const appName = process.env.APP_NAME || 'Redlight';
+      const appName = await getAppName();
       sendCalendarInviteEmail(
         targetUser.email, targetUser.name, from_user,
         title, start_time, end_time, description || null,
diff --git a/server/routes/federation.js b/server/routes/federation.js
index 33ddd08..70fa9b9 100644
--- a/server/routes/federation.js
+++ b/server/routes/federation.js
@@ -6,6 +6,7 @@ import { authenticateToken, getBaseUrl } from '../middleware/auth.js';
 import { sendFederationInviteEmail, sendCalendarEventDeletedEmail } from '../config/mailer.js';
 import { log } from '../config/logger.js';
 import { createNotification } from '../config/notifications.js';
+import { getAppName } from '../config/appName.js';
 
 // M13: rate limit the unauthenticated federation receive endpoint
 const federationReceiveLimiter = rateLimit({
@@ -198,7 +199,7 @@ router.post('/receive', federationReceiveLimiter, async (req, res) => {
 
         // Look up user by name (case-insensitive)
         const targetUser = await db.get(
-            'SELECT id, name, email FROM users WHERE LOWER(name) = LOWER(?)',
+            'SELECT id, name, email, language FROM users WHERE LOWER(name) = LOWER(?)',
             [username]
         );
 
@@ -238,7 +239,7 @@ router.post('/receive', federationReceiveLimiter, async (req, res) => {
         if (targetUser.email) {
             const appUrl = getBaseUrl(req);
             const inboxUrl = `${appUrl}/federation/inbox`;
-            const appName = process.env.APP_NAME || 'Redlight';
+            const appName = await getAppName();
             sendFederationInviteEmail(
                 targetUser.email, targetUser.name, from_user,
                 room_name, message || null, inboxUrl, appName, targetUser.language || 'en'
@@ -627,7 +628,7 @@ router.post('/calendar-event-deleted', federationReceiveLimiter, async (req, res
 
         // Notify affected users by email (fire-and-forget)
         if (affectedUsers.length > 0) {
-            const appName = process.env.APP_NAME || 'Redlight';
+            const appName = await getAppName();
             for (const u of affectedUsers) {
                 sendCalendarEventDeletedEmail(u.email, u.name, u.from_user, u.title, appName, u.language || 'en')
                     .catch(mailErr => {
diff --git a/server/routes/rooms.js b/server/routes/rooms.js
index 9d2750d..18874bd 100644
--- a/server/routes/rooms.js
+++ b/server/routes/rooms.js
@@ -9,6 +9,7 @@ import { authenticateToken, getBaseUrl } from '../middleware/auth.js';
 import { log } from '../config/logger.js';
 import { createNotification } from '../config/notifications.js';
 import { sendGuestInviteEmail } from '../config/mailer.js';
+import { getAppName } from '../config/appName.js';
 import {
   createMeeting,
   joinMeeting,
@@ -513,7 +514,9 @@ router.post('/:uid/start', authenticateToken, async (req, res) => {
     const analyticsCallbackURL = room.learning_analytics
       ? `${baseUrl}/api/analytics/callback/${room.uid}?token=${getAnalyticsToken(room.uid)}`
       : null;
-    await createMeeting(room, baseUrl, loginURL, presentationUrl, analyticsCallbackURL);
+    // Localise BBB's default welcome message in the room owner's language
+    const owner = await db.get('SELECT language FROM users WHERE id = ?', [room.user_id]);
+    await createMeeting(room, baseUrl, loginURL, presentationUrl, analyticsCallbackURL, owner?.language || 'en');
     const avatarURL = getUserAvatarURL(req, req.user);
     const displayName = req.user.display_name || req.user.name;
     const joinUrl = await joinMeeting(room.uid, displayName, true, avatarURL);
@@ -662,7 +665,9 @@ router.post('/:uid/guest-join', guestJoinLimiter, async (req, res) => {
       const analyticsCallbackURL = room.learning_analytics
         ? `${baseUrl}/api/analytics/callback/${room.uid}?token=${getAnalyticsToken(room.uid)}`
         : null;
-      await createMeeting(room, baseUrl, loginURL, null, analyticsCallbackURL);
+      // Localise BBB's default welcome message in the room owner's language
+      const owner = await db.get('SELECT language FROM users WHERE id = ?', [room.user_id]);
+      await createMeeting(room, baseUrl, loginURL, null, analyticsCallbackURL, owner?.language || 'en');
     }
 
     // Check moderator code
@@ -908,7 +913,7 @@ router.post('/invite-email', authenticateToken, async (req, res) => {
       ? `${baseUrl}/join/${room.uid}?ac=${encodeURIComponent(room.access_code)}`
       : `${baseUrl}/join/${room.uid}`;
 
-    const appName = process.env.APP_NAME || 'Redlight';
+    const appName = await getAppName();
     const fromUser = req.user.display_name || req.user.name;
     const lang = req.user.language || 'en';