diff --git a/docs/mail-integration.md b/docs/mail-integration.md
index 92edece..5e4544a 100644
--- a/docs/mail-integration.md
+++ b/docs/mail-integration.md
@@ -35,6 +35,7 @@
 > make mail-sync                                                   # synchro complète
 > docker exec -i -u www-data php-lesstime-fpm php bin/console app:mail:sync --folder=INBOX -v
 > docker exec -i -u www-data php-lesstime-fpm php bin/console messenger:consume async -vv   # worker (fait marcher le bouton)
+> docker exec -i php-lesstime-fpm php bin/console app:mail:redecode-headers [--dry-run]  # re-décode les en-têtes MIME déjà en base (backfill)
 > make test                                                        # 33 tests
 > ```
 > Fixtures `make fixtures` plantent sur un état legacy `workflow_id` (hors-scope mail) — configurer la boîte via l'UI admin.
@@ -45,6 +46,8 @@
 - Navigation par dossiers (arbre récursif avec compteurs non-lus)
 - Liste paginée des messages (infinite scroll, cursor-based)
 - Lecture des corps de mail sanitisés (DOMPurify — protection XSS + pixels tracking)
+- Décodage des en-têtes MIME encodés (RFC 2047, ex `=?UTF-8?Q?...`) sur sujet + nom d'expéditeur (`App\Mail\MimeHeaderDecoder`, appliqué dans `ImapMailProvider`)
+- Aperçu inline des pièces jointes images + PDF (visionneuse modale plein écran), téléchargement pour les autres types
 - Création d'une tâche Lesstime depuis un mail (sujet → titre, texte → description)
 - Lien mail ↔ tâche (bidirectionnel)
 - Onglet "Mails" dans le TaskDrawer pour retrouver les mails liés à une tâche
@@ -107,7 +110,7 @@ Tous les endpoints `/api/mail/*` refusent explicitement `ROLE_CLIENT`.
 
 ### Frontend
 - `frontend/pages/mail.vue` — page principale 3 colonnes
-- `frontend/components/mail/` — MailFolderTree, MailMessageList, MailMessageViewer, MailRefreshButton
+- `frontend/components/mail/` — MailFolderTree, MailMessageList, MailMessageViewer, MailRefreshButton, MailAttachmentPreview (visionneuse modale image/PDF)
 - `frontend/components/admin/AdminMailTab.vue` — onglet config admin
 - `frontend/stores/mail.ts` — store Pinia (folders, messages, polling)
 - `frontend/services/mail.ts` — service API (toutes les méthodes)
diff --git a/frontend/components/mail/MailAttachmentPreview.vue b/frontend/components/mail/MailAttachmentPreview.vue
new file mode 100644
index 0000000..dee9b3f
--- /dev/null
+++ b/frontend/components/mail/MailAttachmentPreview.vue
@@ -0,0 +1,121 @@
+<script setup lang="ts">
+const props = defineProps<{
+    /** Ouverture de la visionneuse. */
+    modelValue: boolean
+    /** Nom du fichier affiché dans la barre. */
+    filename: string
+    /** Type MIME — détermine le rendu (image vs PDF). */
+    mimeType: string
+    /** Object URL du Blob de la pièce jointe. null tant que le contenu charge. */
+    url: string | null
+    /** Téléchargement en cours du contenu. */
+    loading: boolean
+}>()
+
+const emit = defineEmits<{
+    'update:modelValue': [value: boolean]
+    download: []
+}>()
+
+const { t } = useI18n()
+
+const isImage = computed(() => props.mimeType.startsWith('image/'))
+const isPdf = computed(() => props.mimeType === 'application/pdf')
+
+function close(): void {
+    emit('update:modelValue', false)
+}
+
+function onKeydown(e: KeyboardEvent): void {
+    if (e.key === 'Escape') close()
+}
+
+watch(
+    () => props.modelValue,
+    (open) => {
+        if (open) {
+            window.addEventListener('keydown', onKeydown)
+        } else {
+            window.removeEventListener('keydown', onKeydown)
+        }
+    },
+)
+
+onBeforeUnmount(() => window.removeEventListener('keydown', onKeydown))
+</script>
+
+<template>
+    <Teleport v-if="modelValue" to="body">
+        <Transition name="mail-preview" appear>
+            <div class="fixed inset-0 z-50 flex flex-col bg-slate-900/80 backdrop-blur-sm">
+                <!-- Barre supérieure -->
+                <div class="flex flex-shrink-0 items-center justify-between gap-4 px-4 py-3 text-white">
+                    <div class="flex min-w-0 items-center gap-2">
+                        <Icon
+                            :name="isImage ? 'material-symbols:image-outline' : 'material-symbols:picture-as-pdf-outline'"
+                            size="18"
+                            class="flex-shrink-0 text-white/70"
+                        />
+                        <span class="truncate text-sm font-medium">{{ filename }}</span>
+                    </div>
+                    <div class="flex flex-shrink-0 items-center gap-1">
+                        <button
+                            type="button"
+                            class="flex items-center gap-1.5 rounded-md px-3 py-1.5 text-sm text-white/90 transition-colors hover:bg-white/10"
+                            @click="emit('download')"
+                        >
+                            <Icon name="material-symbols:download" size="18" />
+                            <span class="hidden sm:inline">{{ t('mail.actions.download') }}</span>
+                        </button>
+                        <button
+                            type="button"
+                            class="rounded-md p-1.5 text-white/90 transition-colors hover:bg-white/10"
+                            :aria-label="t('mail.preview.close')"
+                            @click="close"
+                        >
+                            <Icon name="mdi:close" size="20" />
+                        </button>
+                    </div>
+                </div>
+
+                <!-- Contenu -->
+                <div class="flex min-h-0 flex-1 items-center justify-center overflow-auto p-4" @click.self="close">
+                    <div v-if="loading" class="flex flex-col items-center gap-3 text-white/70">
+                        <Icon name="material-symbols:progress-activity" size="32" class="animate-spin" />
+                        <span class="text-sm">{{ t('mail.preview.loading') }}</span>
+                    </div>
+
+                    <img
+                        v-else-if="isImage && url"
+                        :src="url"
+                        :alt="filename"
+                        class="max-h-full max-w-full rounded-lg object-contain shadow-2xl"
+                    >
+
+                    <iframe
+                        v-else-if="isPdf && url"
+                        :src="url"
+                        :title="filename"
+                        class="h-full w-full max-w-5xl rounded-lg bg-white shadow-2xl"
+                    />
+
+                    <div v-else class="flex flex-col items-center gap-3 text-white/70">
+                        <Icon name="material-symbols:visibility-off-outline" size="32" />
+                        <span class="text-sm">{{ t('mail.preview.unavailable') }}</span>
+                    </div>
+                </div>
+            </div>
+        </Transition>
+    </Teleport>
+</template>
+
+<style scoped>
+.mail-preview-enter-active,
+.mail-preview-leave-active {
+    transition: opacity 0.2s ease;
+}
+.mail-preview-enter-from,
+.mail-preview-leave-to {
+    opacity: 0;
+}
+</style>
diff --git a/frontend/components/mail/MailMessageViewer.vue b/frontend/components/mail/MailMessageViewer.vue
index 4f2c1cf..34467e1 100644
--- a/frontend/components/mail/MailMessageViewer.vue
+++ b/frontend/components/mail/MailMessageViewer.vue
@@ -1,5 +1,5 @@
 <script setup lang="ts">
-import type { MailMessageDetailDto, MailAddressDto } from '~/services/dto/mail'
+import type { MailMessageDetailDto, MailAddressDto, MailAttachmentDto } from '~/services/dto/mail'
 import { sanitizeMailHtml } from '~/utils/sanitizeMailHtml'
 import { useMailService } from '~/services/mail'
 
@@ -24,22 +24,101 @@ const sanitizedBody = computed((): string => {
     return sanitizeMailHtml(props.detail.bodyHtml, { allowImages: showImages.value })
 })
 
+// ─── Pièces jointes : aperçu / téléchargement ──────────────────────────────
+
+function isImage(mime: string): boolean {
+    return mime.startsWith('image/')
+}
+
+function isPdf(mime: string): boolean {
+    return mime === 'application/pdf'
+}
+
+function isPreviewable(mime: string): boolean {
+    return isImage(mime) || isPdf(mime)
+}
+
+function attachmentIcon(mime: string): string {
+    if (isImage(mime)) return 'material-symbols:image-outline'
+    if (isPdf(mime)) return 'material-symbols:picture-as-pdf-outline'
+    return 'material-symbols:attach-file'
+}
+
+const previewOpen = ref(false)
+const previewLoading = ref(false)
+const previewAtt = ref<MailAttachmentDto | null>(null)
+const previewUrl = ref<string | null>(null)
+let previewBlob: Blob | null = null
+
+function revokePreview(): void {
+    if (previewUrl.value) {
+        URL.revokeObjectURL(previewUrl.value)
+        previewUrl.value = null
+    }
+    previewBlob = null
+}
+
 watch(
     () => props.detail?.header.id,
     () => {
         showImages.value = false
+        previewOpen.value = false
+        revokePreview()
     },
 )
 
+watch(previewOpen, (open) => {
+    if (!open) revokePreview()
+})
+
+onBeforeUnmount(revokePreview)
+
+async function handleAttachmentClick(att: MailAttachmentDto): Promise<void> {
+    if (!isPreviewable(att.mimeType)) {
+        await handleDownload(att.downloadId, att.filename)
+        return
+    }
+
+    previewAtt.value = att
+    previewUrl.value = null
+    previewLoading.value = true
+    previewOpen.value = true
+
+    try {
+        const { data } = await mailService.downloadAttachment(att.downloadId)
+        previewBlob = data
+        previewUrl.value = URL.createObjectURL(data)
+    } catch {
+        // useApi affiche déjà le toast — on referme la visionneuse.
+        previewOpen.value = false
+    } finally {
+        previewLoading.value = false
+    }
+}
+
+function downloadFromPreview(): void {
+    const att = previewAtt.value
+    if (!att) return
+    if (previewBlob) {
+        triggerBlobDownload(previewBlob, att.filename)
+    } else {
+        void handleDownload(att.downloadId, att.filename)
+    }
+}
+
+function triggerBlobDownload(blob: Blob, filename: string): void {
+    const url = URL.createObjectURL(blob)
+    const a = document.createElement('a')
+    a.href = url
+    a.download = filename
+    a.click()
+    URL.revokeObjectURL(url)
+}
+
 async function handleDownload(downloadId: string, filename: string): Promise<void> {
     try {
         const { data } = await mailService.downloadAttachment(downloadId)
-        const url = URL.createObjectURL(data)
-        const a = document.createElement('a')
-        a.href = url
-        a.download = filename
-        a.click()
-        URL.revokeObjectURL(url)
+        triggerBlobDownload(data, filename)
     } catch {
         // L'erreur est gérée par useApi (toast automatique)
     }
@@ -169,15 +248,31 @@ function joinAddresses(addresses: MailAddressDto[]): string {
                         :key="att.downloadId"
                         type="button"
                         class="flex items-center gap-1.5 rounded border border-neutral-200 bg-neutral-50 px-2.5 py-1.5 text-xs text-neutral-700 transition-colors hover:bg-neutral-100 hover:border-neutral-300"
-                        :title="att.filename"
-                        @click="handleDownload(att.downloadId, att.filename)"
+                        :title="isPreviewable(att.mimeType) ? t('mail.preview.open') : t('mail.actions.download')"
+                        @click="handleAttachmentClick(att)"
                     >
-                        <Icon name="material-symbols:attach-file" size="14" class="flex-shrink-0 text-neutral-400" />
+                        <Icon :name="attachmentIcon(att.mimeType)" size="14" class="flex-shrink-0 text-neutral-400" />
                         <span class="max-w-[180px] truncate">{{ att.filename }}</span>
                         <span class="text-neutral-400">({{ Math.round(att.size / 1024) }} Ko)</span>
+                        <Icon
+                            v-if="isPreviewable(att.mimeType)"
+                            name="material-symbols:visibility-outline"
+                            size="13"
+                            class="flex-shrink-0 text-neutral-400"
+                        />
                     </button>
                 </div>
             </div>
+
+            <MailAttachmentPreview
+                v-if="previewAtt"
+                v-model="previewOpen"
+                :filename="previewAtt.filename"
+                :mime-type="previewAtt.mimeType"
+                :url="previewUrl"
+                :loading="previewLoading"
+                @download="downloadFromPreview"
+            />
         </template>
     </div>
 </template>
diff --git a/frontend/i18n/locales/fr.json b/frontend/i18n/locales/fr.json
index acaad58..9dbfba6 100644
--- a/frontend/i18n/locales/fr.json
+++ b/frontend/i18n/locales/fr.json
@@ -528,6 +528,12 @@
             "list": "Aucun message dans ce dossier.",
             "viewer": "Sélectionnez un message pour le lire."
         },
+        "preview": {
+            "open": "Prévisualiser",
+            "close": "Fermer l'aperçu",
+            "loading": "Chargement de l'aperçu…",
+            "unavailable": "Aperçu indisponible pour ce type de fichier."
+        },
         "folderTree": {
             "expand": "Déplier le dossier",
             "collapse": "Replier le dossier"
diff --git a/src/Command/MailRedecodeHeadersCommand.php b/src/Command/MailRedecodeHeadersCommand.php
new file mode 100644
index 0000000..5bb7f59
--- /dev/null
+++ b/src/Command/MailRedecodeHeadersCommand.php
@@ -0,0 +1,84 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Command;
+
+use App\Mail\MimeHeaderDecoder;
+use App\Repository\MailMessageRepository;
+use Doctrine\ORM\EntityManagerInterface;
+use Symfony\Component\Console\Attribute\AsCommand;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+
+#[AsCommand(
+    name: 'app:mail:redecode-headers',
+    description: 'Re-décode les sujets et noms d\'expéditeur encodés en MIME (RFC 2047) déjà stockés en base',
+)]
+final class MailRedecodeHeadersCommand extends Command
+{
+    public function __construct(
+        private readonly MailMessageRepository $messageRepository,
+        private readonly EntityManagerInterface $entityManager,
+    ) {
+        parent::__construct();
+    }
+
+    protected function configure(): void
+    {
+        $this->addOption(
+            'dry-run',
+            null,
+            InputOption::VALUE_NONE,
+            'Affiche les changements sans écrire en base',
+        );
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $io       = new SymfonyStyle($input, $output);
+        $isDryRun = (bool) $input->getOption('dry-run');
+
+        $messages = $this->messageRepository->findAll();
+        $io->text(sprintf('%d message(s) à examiner...', count($messages)));
+
+        $changed = 0;
+
+        foreach ($messages as $message) {
+            $newSubject  = MimeHeaderDecoder::decode($message->getSubject());
+            $newFromName = MimeHeaderDecoder::decode($message->getFromName());
+
+            $hasChange = $newSubject !== $message->getSubject() || $newFromName !== $message->getFromName();
+
+            if (!$hasChange) {
+                continue;
+            }
+
+            if ($io->isVerbose()) {
+                $io->text(sprintf(' - #%d : "%s" → "%s"', $message->getId(), (string) $message->getSubject(), (string) $newSubject));
+            }
+
+            if (!$isDryRun) {
+                $message->setSubject($newSubject);
+                $message->setFromName($newFromName);
+            }
+
+            ++$changed;
+        }
+
+        if (!$isDryRun) {
+            $this->entityManager->flush();
+        }
+
+        $io->success(sprintf(
+            '%s%d en-tête(s) re-décodé(s).',
+            $isDryRun ? '[dry-run] ' : '',
+            $changed,
+        ));
+
+        return Command::SUCCESS;
+    }
+}
diff --git a/src/Mail/ImapMailProvider.php b/src/Mail/ImapMailProvider.php
index 9ef7c45..5db92c8 100644
--- a/src/Mail/ImapMailProvider.php
+++ b/src/Mail/ImapMailProvider.php
@@ -351,7 +351,9 @@ final class ImapMailProvider implements MailProviderInterface
     {
         $from        = $message->getFrom()->first();
         $fromAddress = null !== $from ? (string) $from->mail : '';
-        $fromName    = null !== $from && null !== $from->personal ? (string) $from->personal : null;
+        $fromName    = null !== $from && null !== $from->personal
+            ? MimeHeaderDecoder::decode((string) $from->personal)
+            : null;
 
         $toAddresses = [];
         foreach ($message->getTo() as $addr) {
@@ -388,7 +390,7 @@ final class ImapMailProvider implements MailProviderInterface
         return new MailMessageHeaderDto(
             uid: (int) $message->getUid(),
             messageId: (string) $message->getMessageId(),
-            subject: '' !== (string) $message->getSubject() ? (string) $message->getSubject() : null,
+            subject: '' !== (string) $message->getSubject() ? MimeHeaderDecoder::decode((string) $message->getSubject()) : null,
             fromAddress: $fromAddress,
             fromName: $fromName,
             toAddresses: $toAddresses,
diff --git a/src/Mail/MimeHeaderDecoder.php b/src/Mail/MimeHeaderDecoder.php
new file mode 100644
index 0000000..655282b
--- /dev/null
+++ b/src/Mail/MimeHeaderDecoder.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Mail;
+
+use const ICONV_MIME_DECODE_CONTINUE_ON_ERROR;
+
+/**
+ * Décode les en-têtes mail encodés en « encoded-words » MIME (RFC 2047),
+ * ex: "=?UTF-8?Q?Fwd=3A_Votre_inscription?=" → "Fwd: Votre inscription".
+ *
+ * Certains serveurs IMAP (OVH) renvoient les sujets / noms d'expéditeur
+ * encodés bruts ; webklex ne les décode pas systématiquement. Cet utilitaire
+ * normalise la sortie en UTF-8 lisible. Idempotent : un texte déjà décodé
+ * (sans séquence "=?") est retourné inchangé.
+ */
+final class MimeHeaderDecoder
+{
+    public static function decode(?string $value): ?string
+    {
+        if (null === $value || '' === $value) {
+            return $value;
+        }
+
+        // Pas d'encoded-word → rien à faire (chemin rapide + idempotence).
+        if (!str_contains($value, '=?')) {
+            return $value;
+        }
+
+        $decoded = @iconv_mime_decode($value, ICONV_MIME_DECODE_CONTINUE_ON_ERROR, 'UTF-8');
+
+        if (false === $decoded || '' === trim($decoded)) {
+            // Fallback : mb_decode_mimeheader gère certains cas refusés par iconv.
+            $previous = mb_internal_encoding();
+            mb_internal_encoding('UTF-8');
+
+            try {
+                $decoded = mb_decode_mimeheader($value);
+            } finally {
+                mb_internal_encoding($previous);
+            }
+        }
+
+        return false === $decoded || '' === $decoded ? $value : $decoded;
+    }
+}
diff --git a/tests/Unit/Mail/MimeHeaderDecoderTest.php b/tests/Unit/Mail/MimeHeaderDecoderTest.php
new file mode 100644
index 0000000..75793e3
--- /dev/null
+++ b/tests/Unit/Mail/MimeHeaderDecoderTest.php
@@ -0,0 +1,50 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Tests\Unit\Mail;
+
+use App\Mail\MimeHeaderDecoder;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @internal
+ */
+class MimeHeaderDecoderTest extends TestCase
+{
+    public function testDecodesQEncodedSubject(): void
+    {
+        self::assertSame(
+            'Fwd: Votre inscription',
+            MimeHeaderDecoder::decode('=?UTF-8?Q?Fwd=3A_Votre_inscription?='),
+        );
+    }
+
+    public function testDecodesBEncodedSubjectWithAccents(): void
+    {
+        // "Réunion été" encodé en Base64 UTF-8
+        self::assertSame(
+            'Réunion été',
+            MimeHeaderDecoder::decode('=?UTF-8?B?UsOpdW5pb24gw6l0w6k=?='),
+        );
+    }
+
+    public function testIsIdempotentOnPlainText(): void
+    {
+        self::assertSame('Christian ROY', MimeHeaderDecoder::decode('Christian ROY'));
+        self::assertSame('TR: Bail commercial', MimeHeaderDecoder::decode('TR: Bail commercial'));
+    }
+
+    public function testPreservesNullAndEmpty(): void
+    {
+        self::assertNull(MimeHeaderDecoder::decode(null));
+        self::assertSame('', MimeHeaderDecoder::decode(''));
+    }
+
+    public function testFallsBackToOriginalWhenUndecodable(): void
+    {
+        // Charset inconnu : on ne perd pas la valeur d'origine.
+        $value = '=?unknown-charset?Q?test?=';
+        self::assertNotSame('', MimeHeaderDecoder::decode($value));
+    }
+}