diff --git a/app/[locale]/page.tsx b/app/[locale]/page.tsx
index 225026fb..bb09912a 100644
--- a/app/[locale]/page.tsx
+++ b/app/[locale]/page.tsx
@@ -808,6 +808,17 @@ export default function Home() {
     setActiveView("list");
   };
 
+  // Navigate to next/previous email in the list
+  const selectedEmailIndex = selectedEmail ? emails.findIndex(e => e.id === selectedEmail.id) : -1;
+
+  const handleNavigateNext = selectedEmailIndex >= 0 && selectedEmailIndex < emails.length - 1
+    ? () => handleEmailSelect(emails[selectedEmailIndex + 1])
+    : undefined;
+
+  const handleNavigatePrev = selectedEmailIndex > 0
+    ? () => handleEmailSelect(emails[selectedEmailIndex - 1])
+    : undefined;
+
   // Handle opening conversation view on mobile
   const handleOpenConversation = async (thread: ThreadGroup) => {
     if (!client) return;
@@ -1403,6 +1414,8 @@ export default function Home() {
                       setTabletListVisible(true);
                       selectEmail(null);
                     }}
+                    onNavigateNext={handleNavigateNext}
+                    onNavigatePrev={handleNavigatePrev}
                     onShowShortcuts={() => setShowShortcutsModal(true)}
                     currentUserEmail={client?.["username"]}
                     currentUserName={client?.["username"]?.split("@")[0]}
diff --git a/components/email/email-viewer.tsx b/components/email/email-viewer.tsx
index 411b8e9c..da9a52b1 100644
--- a/components/email/email-viewer.tsx
+++ b/components/email/email-viewer.tsx
@@ -19,6 +19,7 @@ import {
   ChevronDown,
   ChevronUp,
   ChevronLeft,
+  ChevronRight,
   Download,
   Mail,
   Clock,
@@ -89,6 +90,8 @@ interface EmailViewerProps {
   onUndoSpam?: () => void;
   onMoveToMailbox?: (mailboxId: string) => void;
   onBack?: () => void;
+  onNavigateNext?: () => void;
+  onNavigatePrev?: () => void;
   onShowShortcuts?: () => void;
   currentUserEmail?: string;
   currentUserName?: string;
@@ -339,7 +342,7 @@ function ContactSidebarPanel({
                   <div key={i} className="text-sm">
                     {o.name}
                     {o.units && o.units.length > 0 && (
-                      <span className="text-muted-foreground"> — {o.units.map(u => u.name).join(", ")}</span>
+                      <span className="text-muted-foreground"> — {o.units.map(u => u.name).join(", ")}</span>
                     )}
                   </div>
                 ))}
@@ -410,6 +413,8 @@ export function EmailViewer({
   onUndoSpam,
   onMoveToMailbox,
   onBack,
+  onNavigateNext,
+  onNavigatePrev,
   onShowShortcuts,
   currentUserEmail,
   currentUserName,
@@ -438,7 +443,7 @@ export function EmailViewer({
   }));
 
   // Tablet list visibility
-  const { isTablet } = useDeviceDetection();
+  const { isTablet, isMobile } = useDeviceDetection();
   const { tabletListVisible } = useUIStore();
   const { identities, client } = useAuthStore();
   const resolvedTheme = useThemeStore((state) => state.resolvedTheme);
@@ -456,6 +461,8 @@ export function EmailViewer({
   const moreMenuRef = useRef<HTMLDivElement>(null);
   const tagMenuRef = useRef<HTMLDivElement>(null);
   const moveMenuRef = useRef<HTMLDivElement>(null);
+  const toolbarRef = useRef<HTMLDivElement>(null);
+  const [overflowCount, setOverflowCount] = useState(0);
   const currentColor = getCurrentColor(email?.keywords);
 
   // Build mailbox tree for move-to dropdown
@@ -522,6 +529,41 @@ export function EmailViewer({
     setMoveMenuOpen(false);
   }, [email?.id]);
 
+  // Dynamically detect which toolbar items overflow and should move to the More menu
+  useEffect(() => {
+    const el = toolbarRef.current;
+    if (!el) return;
+    const calculate = () => {
+      const items = Array.from(el.querySelectorAll<HTMLElement>('[data-overflow-item]'));
+      if (items.length === 0) return;
+      // Sort descending by priority so highest number (least important) is first
+      items.sort((a, b) =>
+        Number(b.dataset.overflowPriority || 0) - Number(a.dataset.overflowPriority || 0)
+      );
+      // Show all items to measure their natural widths
+      items.forEach(item => { item.style.display = ''; });
+      const containerWidth = el.clientWidth;
+      const leftGroup = el.firstElementChild as HTMLElement;
+      const rightGroup = el.lastElementChild as HTMLElement;
+      const mainGap = parseFloat(getComputedStyle(el).gap) || 0;
+      // Iteratively hide items until content fits
+      let count = 0;
+      const isOverflowing = () =>
+        leftGroup.scrollWidth + rightGroup.scrollWidth + mainGap > containerWidth + 1;
+      for (const item of items) {
+        if (!isOverflowing()) break;
+        // Skip items already hidden by CSS (e.g., on mobile)
+        if (item.offsetWidth === 0) continue;
+        item.style.display = 'none';
+        count++;
+      }
+      setOverflowCount(prev => prev === count ? prev : count);
+    };
+    const observer = new ResizeObserver(calculate);
+    observer.observe(el);
+    return () => observer.disconnect();
+  }, [toolbarPosition]);
+
   // Contact sidebar state
   const [contactSidebarEmail, setContactSidebarEmail] = useState<string | null>(null);
   const contacts = useContactStore((s) => s.contacts);
@@ -1063,6 +1105,144 @@ export function EmailViewer({
       key={email.id}
       className={cn("flex-1 flex flex-row h-full bg-background overflow-hidden animate-in fade-in duration-300 relative", className)}
     >
+    {/* Mobile More menu sidebar overlay */}
+    {isMobile && moreMenuOpen && (
+      <div
+        className="fixed inset-0 bg-black/50 z-[60] sm:hidden"
+        onClick={() => setMoreMenuOpen(false)}
+      />
+    )}
+    {isMobile && (
+      <div className={cn(
+        "fixed inset-y-0 right-0 w-72 bg-background border-l border-border z-[70] sm:hidden",
+        "transform transition-transform duration-300 ease-in-out",
+        "flex flex-col",
+        moreMenuOpen ? "translate-x-0" : "translate-x-full"
+      )}>
+        <div className="flex items-center justify-between px-4 py-3 border-b border-border">
+          <span className="text-sm font-semibold text-foreground">{t('more_actions')}</span>
+          <Button variant="ghost" size="icon" onClick={() => setMoreMenuOpen(false)} className="h-9 w-9">
+            <X className="w-5 h-5" />
+          </Button>
+        </div>
+        <div className="flex-1 overflow-y-auto py-2">
+          <button
+            onClick={() => { onArchive?.(); setMoreMenuOpen(false); }}
+            className="w-full px-4 py-3 min-h-[44px] text-sm text-left hover:bg-muted text-foreground flex items-center gap-3"
+          >
+            <Archive className="w-5 h-5" />
+            {t('archive')}
+          </button>
+          {(onMarkAsSpam || onUndoSpam) && (
+            <button
+              onClick={() => { (isInJunkFolder ? onUndoSpam : onMarkAsSpam)?.(); setMoreMenuOpen(false); }}
+              className="w-full px-4 py-3 min-h-[44px] text-sm text-left hover:bg-muted text-foreground flex items-center gap-3"
+            >
+              {isInJunkFolder ? (
+                <ShieldCheck className="h-5 w-5 text-green-600 dark:text-green-400" />
+              ) : (
+                <ShieldAlert className="h-5 w-5 text-red-600 dark:text-red-400" />
+              )}
+              {isInJunkFolder ? t('spam.not_spam_title') : t('spam.button_title')}
+            </button>
+          )}
+          {/* Move to folder */}
+          {moveTree.length > 0 && onMoveToMailbox && (
+            <>
+              <div className="h-px bg-border my-1" />
+              <div className="px-4 py-2 text-xs font-medium text-muted-foreground uppercase tracking-wider">{t('move_to')}</div>
+              {(() => {
+                const renderMobileNodes = (nodes: MailboxNode[], depth = 0) => {
+                  return nodes.map((node) => {
+                    const Icon = getMoveMailboxIcon(node.role);
+                    const isTarget = moveTargetIds.has(node.id);
+                    return (
+                      <div key={node.id}>
+                        {isTarget ? (
+                          <button
+                            onClick={() => { onMoveToMailbox(node.id); setMoreMenuOpen(false); }}
+                            className="w-full px-4 py-2.5 min-h-[44px] text-sm text-left hover:bg-muted flex items-center gap-3"
+                            style={{ paddingLeft: `${1 + depth * 1}rem` }}
+                          >
+                            <Icon className="w-5 h-5 flex-shrink-0" />
+                            <span className="truncate">{node.name}</span>
+                          </button>
+                        ) : (
+                          <div
+                            className="px-4 py-2.5 min-h-[44px] text-sm flex items-center gap-3 text-muted-foreground"
+                            style={{ paddingLeft: `${1 + depth * 1}rem` }}
+                          >
+                            <Icon className="w-5 h-5 flex-shrink-0" />
+                            <span>{node.name}</span>
+                          </div>
+                        )}
+                        {node.children.length > 0 && renderMobileNodes(node.children, depth + 1)}
+                      </div>
+                    );
+                  });
+                };
+                return renderMobileNodes(moveTree);
+              })()}
+              <div className="h-px bg-border my-1" />
+            </>
+          )}
+          {/* Tags */}
+          {colorOptions.length > 0 && (
+            <>
+              <div className="h-px bg-border my-1" />
+              <div className="px-4 py-2 text-xs font-medium text-muted-foreground uppercase tracking-wider">{t('tag')}</div>
+              {colorOptions.map((option) => (
+                <button
+                  key={option.value}
+                  onClick={() => { if (email) onSetColorTag?.(email.id, option.value); setMoreMenuOpen(false); }}
+                  className={cn(
+                    "w-full px-4 py-2.5 min-h-[44px] text-sm text-left hover:bg-muted flex items-center gap-3",
+                    currentColor === option.value && "bg-accent font-medium"
+                  )}
+                >
+                  <span className={cn("w-3.5 h-3.5 rounded-full flex-shrink-0", option.color)} />
+                  <span className="truncate">{option.name}</span>
+                  {currentColor === option.value && <Check className="w-4 h-4 ml-auto flex-shrink-0 text-foreground" />}
+                </button>
+              ))}
+              {currentColor && (
+                <button
+                  onClick={() => { if (email) onSetColorTag?.(email.id, null); setMoreMenuOpen(false); }}
+                  className="w-full px-4 py-2.5 min-h-[44px] text-sm text-left hover:bg-muted flex items-center gap-3 text-muted-foreground"
+                >
+                  <X className="w-4 h-4 flex-shrink-0" />
+                  <span>{t('remove_color')}</span>
+                </button>
+              )}
+              <div className="h-px bg-border my-1" />
+            </>
+          )}
+          <button
+            onClick={() => { handlePrint(); setMoreMenuOpen(false); }}
+            className="w-full px-4 py-3 min-h-[44px] text-sm text-left hover:bg-muted text-foreground flex items-center gap-3"
+          >
+            <Printer className="w-5 h-5" />
+            {t('print')}
+          </button>
+          <button
+            onClick={() => { setShowSourceModal(true); setMoreMenuOpen(false); }}
+            className="w-full px-4 py-3 min-h-[44px] text-sm text-left hover:bg-muted text-foreground flex items-center gap-3"
+          >
+            <Code className="w-5 h-5" />
+            {t('view_source')}
+          </button>
+          {onShowShortcuts && (
+            <button
+              onClick={() => { onShowShortcuts(); setMoreMenuOpen(false); }}
+              className="w-full px-4 py-3 min-h-[44px] text-sm text-left hover:bg-muted text-foreground flex items-center gap-3"
+            >
+              <Keyboard className="w-5 h-5" />
+              {t('keyboard_shortcuts')}
+            </button>
+          )}
+        </div>
+      </div>
+    )}
     {/* Main email content */}
     <div className="flex-1 flex flex-col h-full overflow-hidden min-w-0">
       {/* Loading overlay when fetching new email */}
@@ -1081,7 +1261,7 @@ export function EmailViewer({
           "max-lg:sticky max-lg:top-0 max-lg:z-10"
         )}>
           <div className="px-2 sm:px-4 lg:px-6 py-1 sm:py-2">
-            <div className="flex items-center justify-between gap-0.5 sm:gap-2">
+            <div ref={toolbarRef} className="flex items-center justify-between gap-0.5 sm:gap-2">
               {/* Left: Back + Reply actions */}
               <div className="flex items-center gap-0 sm:gap-1">
                 {isTablet && !tabletListVisible && onBack && (
@@ -1099,31 +1279,31 @@ export function EmailViewer({
                   variant="ghost"
                   size="sm"
                   onClick={() => onReply?.()}
-                  className="flex-col items-center gap-0.5 h-auto py-1.5 px-2 sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0"
+                  className="hidden sm:flex sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0"
                   title={t('tooltips.reply')}
                 >
                   <Reply className="w-4 h-4" />
-                  <span className="text-[10px] leading-tight sm:text-sm">{t('reply')}</span>
+                  <span className="hidden sm:inline text-sm">{t('reply')}</span>
                 </Button>
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={onReplyAll}
-                  className="flex-col items-center gap-0.5 h-auto py-1.5 px-1.5 sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0 sm:px-3"
+                  className="hidden sm:flex sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0 sm:px-3"
                   title={t('tooltips.reply_all')}
                 >
                   <ReplyAll className="w-4 h-4" />
-                  <span className="text-[10px] leading-tight sm:text-sm">{t('reply_all')}</span>
+                  <span className="hidden sm:inline text-sm">{t('reply_all')}</span>
                 </Button>
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={onForward}
-                  className="flex-col items-center gap-0.5 h-auto py-1.5 px-2 sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0"
+                  className="hidden sm:flex sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0"
                   title={t('tooltips.forward')}
                 >
                   <Forward className="w-4 h-4" />
-                  <span className="text-[10px] leading-tight sm:text-sm">{t('forward')}</span>
+                  <span className="hidden sm:inline text-sm">{t('forward')}</span>
                 </Button>
               </div>
 
@@ -1134,11 +1314,13 @@ export function EmailViewer({
                     <Loader2 className="w-4 h-4 animate-spin" />
                   </div>
                 )}
-                {/* Archive - hidden on mobile, available in More menu */}
+                {/* Archive - hidden on mobile, overflows to More menu */}
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={onArchive}
+                  data-overflow-item
+                  data-overflow-priority="1"
                   className="hidden sm:inline-flex h-8 gap-1.5"
                   title={t('tooltips.archive')}
                 >
@@ -1155,12 +1337,14 @@ export function EmailViewer({
                   <Trash2 className="w-4 h-4" />
                   <span className="text-[10px] leading-tight sm:text-sm">{t('delete')}</span>
                 </Button>
-                {/* Spam - hidden on mobile, available in More menu */}
+                {/* Spam - hidden on mobile, overflows to More menu */}
                 {(onMarkAsSpam || onUndoSpam) && (
                   <Button
                     variant="ghost"
                     size="sm"
                     onClick={isInJunkFolder ? onUndoSpam : onMarkAsSpam}
+                    data-overflow-item
+                    data-overflow-priority="2"
                     className={cn(
                       "hidden sm:inline-flex h-8 gap-1.5",
                       isInJunkFolder ? "hover:bg-green-50 dark:hover:bg-green-950/30" : "hover:bg-red-50 dark:hover:bg-red-950/30"
@@ -1174,9 +1358,9 @@ export function EmailViewer({
                     )}
                   </Button>
                 )}
-                {/* Move to folder - hidden on mobile, available in More menu */}
+                {/* Move to folder - hidden on mobile, overflows to More menu */}
                 {moveTree.length > 0 && onMoveToMailbox && (
-                  <div ref={moveMenuRef} className="relative hidden sm:block">
+                  <div ref={moveMenuRef} data-overflow-item data-overflow-priority="3" className="relative hidden sm:block">
                     <button
                       onClick={() => { setMoveMenuOpen(!moveMenuOpen); setMoreMenuOpen(false); setTagMenuOpen(false); }}
                       className="h-8 rounded hover:bg-muted flex items-center gap-1.5 px-2"
@@ -1237,10 +1421,10 @@ export function EmailViewer({
                   <span className="text-[10px] leading-tight sm:hidden">{isStarred ? t('tooltips.unstar') : t('tooltips.star')}</span>
                 </Button>
 
-                <div className="w-px h-5 bg-border mx-0.5 hidden sm:block" />
-
-                {/* Tag Picker - click-based, hidden on mobile (available in More menu) */}
-                <div ref={tagMenuRef} className="relative hidden sm:block">
+                {/* Tag Picker + Divider - hidden on mobile, overflows to More menu */}
+                <div data-overflow-item data-overflow-priority="4" className="hidden sm:flex items-center">
+                <div className="w-px h-5 bg-border mx-0.5" />
+                <div ref={tagMenuRef} className="relative">
                   <button
                     onClick={() => { setTagMenuOpen(!tagMenuOpen); setMoreMenuOpen(false); setMoveMenuOpen(false); }}
                     className={cn(
@@ -1296,12 +1480,15 @@ export function EmailViewer({
                     </div>
                   )}
                 </div>
+                </div>
 
-                {/* Print - hidden on mobile, available in More menu */}
+                {/* Print - hidden on mobile, overflows to More menu */}
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={handlePrint}
+                  data-overflow-item
+                  data-overflow-priority="5"
                   className="hidden sm:inline-flex h-8 gap-1.5"
                   title={t('print')}
                 >
@@ -1321,12 +1508,12 @@ export function EmailViewer({
                     <MoreVertical className="w-4 h-4 text-muted-foreground" />
                     <span className="text-[10px] leading-tight sm:hidden">{t('more_actions')}</span>
                   </Button>
-                  {moreMenuOpen && (
+                  {moreMenuOpen && !isMobile && (
                     <div className="absolute right-0 top-full mt-1 w-48 bg-background rounded-md shadow-lg border border-border z-10">
-                      {/* Mobile-only actions */}
+                      {/* Overflow actions - shown when hidden from toolbar or on mobile */}
                       <button
                         onClick={() => { onArchive?.(); setMoreMenuOpen(false); }}
-                        className="w-full px-3 py-2.5 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2 sm:hidden"
+                        className={cn("w-full px-3 py-2.5 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2", overflowCount >= 5 ? "" : "sm:hidden")}
                       >
                         <Archive className="w-4 h-4" />
                         {t('archive')}
@@ -1334,7 +1521,7 @@ export function EmailViewer({
                       {(onMarkAsSpam || onUndoSpam) && (
                         <button
                           onClick={() => { (isInJunkFolder ? onUndoSpam : onMarkAsSpam)?.(); setMoreMenuOpen(false); }}
-                          className="w-full px-3 py-2.5 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2 sm:hidden"
+                          className={cn("w-full px-3 py-2.5 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2", overflowCount >= 4 ? "" : "sm:hidden")}
                         >
                           {isInJunkFolder ? (
                             <ShieldCheck className="h-4 w-4 text-green-600 dark:text-green-400" />
@@ -1344,9 +1531,9 @@ export function EmailViewer({
                           {isInJunkFolder ? t('spam.not_spam_title') : t('spam.button_title')}
                         </button>
                       )}
-                      {/* Move to folder submenu on mobile */}
+                      {/* Move to folder submenu */}
                       {moveTree.length > 0 && onMoveToMailbox && (
-                        <div className="sm:hidden">
+                        <div className={cn(overflowCount >= 3 ? "" : "sm:hidden")}>
                           <div className="h-px bg-border my-1" />
                           <div className="px-3 py-1.5 text-xs font-medium text-muted-foreground uppercase tracking-wider">{t('move_to')}</div>
                           {(() => {
@@ -1383,9 +1570,9 @@ export function EmailViewer({
                           })()}
                           <div className="h-px bg-border my-1" />
                         </div>
-                      )}                      {/* Tag submenu on mobile */}
+                      )}                      {/* Tag submenu */}
                       {colorOptions.length > 0 && (
-                        <div className="sm:hidden">
+                        <div className={cn(overflowCount >= 2 ? "" : "sm:hidden")}>
                           <div className="h-px bg-border my-1" />
                           <div className="px-3 py-1.5 text-xs font-medium text-muted-foreground uppercase tracking-wider">{t('tag')}</div>
                           {colorOptions.map((option) => (
@@ -1416,7 +1603,7 @@ export function EmailViewer({
                       )}
                       <button
                         onClick={() => { handlePrint(); setMoreMenuOpen(false); }}
-                        className="w-full px-3 py-2.5 sm:py-2 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2"
+                        className={cn("w-full px-3 py-2.5 sm:py-2 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2", overflowCount >= 1 ? "" : "sm:hidden")}
                       >
                         <Printer className="w-4 h-4" />
                         {t('print')}
@@ -1519,38 +1706,38 @@ export function EmailViewer({
       {toolbarPosition === 'below-subject' && (
         <div className="bg-background border-b border-border">
           <div className="px-2 sm:px-4 lg:px-6 py-1 sm:py-1.5">
-            <div className="flex items-center justify-between gap-0.5 sm:gap-2">
+            <div ref={toolbarRef} className="flex items-center justify-between gap-0.5 sm:gap-2">
               {/* Left: Reply actions */}
               <div className="flex items-center gap-0 sm:gap-0.5">
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={() => onReply?.()}
-                  className="flex-col items-center gap-0.5 h-auto py-1.5 px-2 sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0"
+                  className="hidden sm:flex sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0"
                   title={t('tooltips.reply')}
                 >
                   <Reply className="w-4 h-4" />
-                  <span className="text-[10px] leading-tight sm:text-sm">{t('reply')}</span>
+                  <span className="hidden sm:inline text-sm">{t('reply')}</span>
                 </Button>
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={onReplyAll}
-                  className="flex-col items-center gap-0.5 h-auto py-1.5 px-1.5 sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0 sm:px-3"
+                  className="hidden sm:flex sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0 sm:px-3"
                   title={t('tooltips.reply_all')}
                 >
                   <ReplyAll className="w-4 h-4" />
-                  <span className="text-[10px] leading-tight sm:text-sm">{t('reply_all')}</span>
+                  <span className="hidden sm:inline text-sm">{t('reply_all')}</span>
                 </Button>
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={onForward}
-                  className="flex-col items-center gap-0.5 h-auto py-1.5 px-2 sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0"
+                  className="hidden sm:flex sm:flex-row sm:h-8 sm:gap-1.5 sm:py-0"
                   title={t('tooltips.forward')}
                 >
                   <Forward className="w-4 h-4" />
-                  <span className="text-[10px] leading-tight sm:text-sm">{t('forward')}</span>
+                  <span className="hidden sm:inline text-sm">{t('forward')}</span>
                 </Button>
               </div>
 
@@ -1561,23 +1748,27 @@ export function EmailViewer({
                     <Loader2 className="w-4 h-4 animate-spin" />
                   </div>
                 )}
-                {/* Archive - hidden on mobile, available in More menu */}
+                {/* Archive - hidden on mobile, overflows to More menu */}
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={onArchive}
+                  data-overflow-item
+                  data-overflow-priority="1"
                   className="hidden sm:inline-flex h-8 gap-1.5"
                   title={t('tooltips.archive')}
                 >
                   <Archive className="w-4 h-4" />
                   <span className="hidden sm:inline text-sm">{t('archive')}</span>
                 </Button>
-                {/* Spam - hidden on mobile, available in More menu */}
+                {/* Spam - hidden on mobile, overflows to More menu */}
                 {(onMarkAsSpam || onUndoSpam) && (
                   <Button
                     variant="ghost"
                     size="sm"
                     onClick={isInJunkFolder ? onUndoSpam : onMarkAsSpam}
+                    data-overflow-item
+                    data-overflow-priority="2"
                     className={cn(
                       "hidden sm:inline-flex h-8 gap-1.5",
                       isInJunkFolder ? "hover:bg-green-50 dark:hover:bg-green-950/30" : "hover:bg-red-50 dark:hover:bg-red-950/30"
@@ -1591,9 +1782,9 @@ export function EmailViewer({
                     )}
                   </Button>
                 )}
-                {/* Move to folder - hidden on mobile, available in More menu */}
+                {/* Move to folder - hidden on mobile, overflows to More menu */}
                 {moveTree.length > 0 && onMoveToMailbox && (
-                  <div ref={moveMenuRef} className="relative hidden sm:block">
+                  <div ref={moveMenuRef} data-overflow-item data-overflow-priority="3" className="relative hidden sm:block">
                     <button
                       onClick={() => { setMoveMenuOpen(!moveMenuOpen); setMoreMenuOpen(false); setTagMenuOpen(false); }}
                       className="h-8 rounded hover:bg-muted flex items-center gap-1.5 px-2"
@@ -1664,10 +1855,10 @@ export function EmailViewer({
                   <span className="text-[10px] leading-tight sm:hidden">{isStarred ? t('tooltips.unstar') : t('tooltips.star')}</span>
                 </Button>
 
-                <div className="w-px h-5 bg-border mx-0.5 hidden sm:block" />
-
-                {/* Tag Picker - click-based, hidden on mobile (available in More menu) */}
-                <div ref={tagMenuRef} className="relative hidden sm:block">
+                {/* Tag Picker + Divider - hidden on mobile, overflows to More menu */}
+                <div data-overflow-item data-overflow-priority="4" className="hidden sm:flex items-center">
+                <div className="w-px h-5 bg-border mx-0.5" />
+                <div ref={tagMenuRef} className="relative">
                   <button
                     onClick={() => { setTagMenuOpen(!tagMenuOpen); setMoreMenuOpen(false); setMoveMenuOpen(false); }}
                     className={cn(
@@ -1723,12 +1914,15 @@ export function EmailViewer({
                     </div>
                   )}
                 </div>
+                </div>
 
-                {/* Print - hidden on mobile, available in More menu */}
+                {/* Print - hidden on mobile, overflows to More menu */}
                 <Button
                   variant="ghost"
                   size="sm"
                   onClick={handlePrint}
+                  data-overflow-item
+                  data-overflow-priority="5"
                   className="hidden sm:inline-flex h-8 gap-1.5"
                   title={t('print')}
                 >
@@ -1748,12 +1942,12 @@ export function EmailViewer({
                     <MoreVertical className="w-4 h-4 text-muted-foreground" />
                     <span className="text-[10px] leading-tight sm:hidden">{t('more_actions')}</span>
                   </Button>
-                  {moreMenuOpen && (
+                  {moreMenuOpen && !isMobile && (
                     <div className="absolute right-0 top-full mt-1 w-48 bg-background rounded-md shadow-lg border border-border z-10">
-                      {/* Mobile-only actions */}
+                      {/* Overflow actions - shown when hidden from toolbar or on mobile */}
                       <button
                         onClick={() => { onArchive?.(); setMoreMenuOpen(false); }}
-                        className="w-full px-3 py-2.5 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2 sm:hidden"
+                        className={cn("w-full px-3 py-2.5 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2", overflowCount >= 5 ? "" : "sm:hidden")}
                       >
                         <Archive className="w-4 h-4" />
                         {t('archive')}
@@ -1761,7 +1955,7 @@ export function EmailViewer({
                       {(onMarkAsSpam || onUndoSpam) && (
                         <button
                           onClick={() => { (isInJunkFolder ? onUndoSpam : onMarkAsSpam)?.(); setMoreMenuOpen(false); }}
-                          className="w-full px-3 py-2.5 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2 sm:hidden"
+                          className={cn("w-full px-3 py-2.5 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2", overflowCount >= 4 ? "" : "sm:hidden")}
                         >
                           {isInJunkFolder ? (
                             <ShieldCheck className="h-4 w-4 text-green-600 dark:text-green-400" />
@@ -1771,9 +1965,9 @@ export function EmailViewer({
                           {isInJunkFolder ? t('spam.not_spam_title') : t('spam.button_title')}
                         </button>
                       )}
-                      {/* Move to folder submenu on mobile */}
+                      {/* Move to folder submenu */}
                       {moveTree.length > 0 && onMoveToMailbox && (
-                        <div className="sm:hidden">
+                        <div className={cn(overflowCount >= 3 ? "" : "sm:hidden")}>
                           <div className="h-px bg-border my-1" />
                           <div className="px-3 py-1.5 text-xs font-medium text-muted-foreground uppercase tracking-wider">{t('move_to')}</div>
                           {(() => {
@@ -1810,9 +2004,9 @@ export function EmailViewer({
                           })()}
                           <div className="h-px bg-border my-1" />
                         </div>
-                      )}                      {/* Tag submenu on mobile */}
+                      )}                      {/* Tag submenu */}
                       {colorOptions.length > 0 && (
-                        <div className="sm:hidden">
+                        <div className={cn(overflowCount >= 2 ? "" : "sm:hidden")}>
                           <div className="h-px bg-border my-1" />
                           <div className="px-3 py-1.5 text-xs font-medium text-muted-foreground uppercase tracking-wider">{t('tag')}</div>
                           {colorOptions.map((option) => (
@@ -1843,7 +2037,7 @@ export function EmailViewer({
                       )}
                       <button
                         onClick={() => { handlePrint(); setMoreMenuOpen(false); }}
-                        className="w-full px-3 py-2.5 sm:py-2 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2"
+                        className={cn("w-full px-3 py-2.5 sm:py-2 text-sm text-left hover:bg-muted text-foreground flex items-center gap-2", overflowCount >= 1 ? "" : "sm:hidden")}
                       >
                         <Printer className="w-4 h-4" />
                         {t('print')}
@@ -2403,7 +2597,7 @@ export function EmailViewer({
       )}
 
       {/* Email Content Area */}
-      <div className="flex-1 overflow-auto bg-muted/30">
+      <div className={cn("flex-1 overflow-auto bg-muted/30", isMobile && "pb-16")}>
         {/* Mobile/Tablet Sender Info - scrolls with content */}
         <div className="lg:hidden bg-background border-b border-border px-4" style={{ paddingBlock: 'var(--density-header-py)' }}>
           <div className="flex items-start" style={{ gap: 'var(--density-item-gap)' }}>
@@ -2446,12 +2640,12 @@ export function EmailViewer({
                         }}
                       />
                     )}
-                    <span>·</span>
+                    <span>·</span>
                   </>
                 )}
                 {email.to && email.to.length > 0 && (
                   <>
-                    <span>→ {t('recipient_to_prefix')}</span>
+                    <span>→ {t('recipient_to_prefix')}</span>
                     {renderClickableRecipients(email.to, currentUserEmail, t, handleViewContactSidebar)}
                   </>
                 )}
@@ -2693,6 +2887,62 @@ export function EmailViewer({
       )}
     </div>
 
+    {/* Mobile bottom action bar */}
+    {isMobile && (
+      <nav className="fixed bottom-0 left-0 right-0 z-[50] bg-background border-t border-border sm:hidden">
+        <div className="flex items-center justify-around">
+          <button
+            onClick={onNavigatePrev}
+            disabled={!onNavigatePrev}
+            className={cn(
+              "flex flex-col items-center justify-center gap-1 py-2 px-3 min-w-[64px] min-h-[44px] transition-colors duration-150",
+              onNavigatePrev ? "text-muted-foreground active:text-foreground" : "text-muted-foreground/30"
+            )}
+            aria-label={t('tooltips.previous')}
+          >
+            <ChevronLeft className="w-5 h-5" />
+            <span className="text-[10px] font-medium leading-tight">{t('previous')}</span>
+          </button>
+          <button
+            onClick={() => onReply?.()}
+            className="flex flex-col items-center justify-center gap-1 py-2 px-3 min-w-[64px] min-h-[44px] text-muted-foreground active:text-foreground transition-colors duration-150"
+            aria-label={t('tooltips.reply')}
+          >
+            <Reply className="w-5 h-5" />
+            <span className="text-[10px] font-medium leading-tight">{t('reply')}</span>
+          </button>
+          <button
+            onClick={onReplyAll}
+            className="flex flex-col items-center justify-center gap-1 py-2 px-3 min-w-[64px] min-h-[44px] text-muted-foreground active:text-foreground transition-colors duration-150"
+            aria-label={t('tooltips.reply_all')}
+          >
+            <ReplyAll className="w-5 h-5" />
+            <span className="text-[10px] font-medium leading-tight">{t('reply_all')}</span>
+          </button>
+          <button
+            onClick={onForward}
+            className="flex flex-col items-center justify-center gap-1 py-2 px-3 min-w-[64px] min-h-[44px] text-muted-foreground active:text-foreground transition-colors duration-150"
+            aria-label={t('tooltips.forward')}
+          >
+            <Forward className="w-5 h-5" />
+            <span className="text-[10px] font-medium leading-tight">{t('forward')}</span>
+          </button>
+          <button
+            onClick={onNavigateNext}
+            disabled={!onNavigateNext}
+            className={cn(
+              "flex flex-col items-center justify-center gap-1 py-2 px-3 min-w-[64px] min-h-[44px] transition-colors duration-150",
+              onNavigateNext ? "text-muted-foreground active:text-foreground" : "text-muted-foreground/30"
+            )}
+            aria-label={t('tooltips.next')}
+          >
+            <ChevronRight className="w-5 h-5" />
+            <span className="text-[10px] font-medium leading-tight">{t('next')}</span>
+          </button>
+        </div>
+      </nav>
+    )}
+
     {/* Contact Detail Sidebar - desktop only */}
     {contactSidebarEmail && !isMobileDevice && (
       <ContactSidebarPanel
diff --git a/locales/en/common.json b/locales/en/common.json
index 20be071b..55f158a1 100644
--- a/locales/en/common.json
+++ b/locales/en/common.json
@@ -175,6 +175,8 @@
     "set_color": "Set tag",
     "tag": "Tag",
     "more_actions": "More actions",
+    "previous": "Prev",
+    "next": "Next",
     "move_to": "Move to...",
     "remove_color": "Remove tag",
     "more_count": "+{count} more",
@@ -251,7 +253,9 @@
       "delete": "Delete (# or Del)",
       "star": "Star (s)",
       "unstar": "Unstar (s)",
-      "compose": "Compose (c)"
+      "compose": "Compose (c)",
+      "previous": "Previous email",
+      "next": "Next email"
     },
     "spam": {
       "button_title": "Report spam",