diff --git a/frontend/components/mail/MailMessageViewer.vue b/frontend/components/mail/MailMessageViewer.vue
new file mode 100644
index 0000000..ab053ea
--- /dev/null
+++ b/frontend/components/mail/MailMessageViewer.vue
@@ -0,0 +1,213 @@
+<script setup lang="ts">
+import type { MailMessageDetailDto, MailAddressDto } from '~/services/dto/mail'
+import { sanitizeMailHtml } from '~/utils/sanitizeMailHtml'
+import { useMailService } from '~/services/mail'
+import { useMailStore } from '~/stores/mail'
+
+const props = defineProps<{
+    /** Détail complet du message. null = aucun message sélectionné. */
+    detail: MailMessageDetailDto | null
+    loading: boolean
+}>()
+
+const emit = defineEmits<{
+    createTask: [mailId: number]
+    linkTask: [mailId: number]
+}>()
+
+const { t } = useI18n()
+const store = useMailStore()
+const mailService = useMailService()
+
+const showImages = ref(false)
+
+const sanitizedBody = computed((): string => {
+    if (!props.detail?.bodyHtml) return ''
+    return sanitizeMailHtml(props.detail.bodyHtml, { allowImages: showImages.value })
+})
+
+watch(
+    () => props.detail?.header.id,
+    () => {
+        showImages.value = false
+    },
+)
+
+async function handleMarkReadToggle(): Promise<void> {
+    if (!props.detail) return
+    const id = props.detail.header.id
+    const currentlyRead = props.detail.header.isRead
+    await store.markRead(id, !currentlyRead)
+}
+
+async function handleFlagToggle(): Promise<void> {
+    if (!props.detail) return
+    const id = props.detail.header.id
+    const currentlyFlagged = props.detail.header.isFlagged
+    await store.markFlagged(id, !currentlyFlagged)
+}
+
+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)
+    } catch {
+        // L'erreur est gérée par useApi (toast automatique)
+    }
+}
+
+function formatDate(iso: string | null): string {
+    if (!iso) return ''
+    return new Date(iso).toLocaleString('fr', {
+        dateStyle: 'long',
+        timeStyle: 'short',
+    })
+}
+
+function joinAddresses(addresses: MailAddressDto[]): string {
+    return addresses
+        .map((a) => (a.name ? `${a.name} <${a.email}>` : a.email))
+        .join(', ')
+}
+</script>
+
+<template>
+    <div class="flex h-full flex-col overflow-hidden">
+        <div
+            v-if="!detail && !loading"
+            class="flex flex-1 items-center justify-center text-sm text-neutral-400 italic px-8 text-center"
+        >
+            {{ t('mail.empty.viewer') }}
+        </div>
+
+        <div v-else-if="loading" class="flex flex-1 items-center justify-center">
+            <Icon name="material-symbols:progress-activity" size="28" class="animate-spin text-neutral-400" />
+        </div>
+
+        <template v-else-if="detail">
+            <div class="flex-shrink-0 border-b border-neutral-200 px-4 py-3 space-y-1.5">
+                <h2 class="text-base font-semibold text-neutral-900 break-words">
+                    {{ detail.header.subject ?? t('mail.noSubject') }}
+                </h2>
+
+                <dl class="text-xs text-neutral-500 space-y-0.5">
+                    <div class="flex gap-1.5">
+                        <dt class="font-medium text-neutral-600 w-5 flex-shrink-0">{{ t('mail.from') }}</dt>
+                        <dd class="break-all">
+                            {{
+                                detail.header.fromName
+                                    ? `${detail.header.fromName} <${detail.header.fromEmail}>`
+                                    : (detail.header.fromEmail ?? '')
+                            }}
+                        </dd>
+                    </div>
+                    <div v-if="detail.header.toRecipients.length > 0" class="flex gap-1.5">
+                        <dt class="font-medium text-neutral-600 w-5 flex-shrink-0">{{ t('mail.to') }}</dt>
+                        <dd class="break-all">{{ joinAddresses(detail.header.toRecipients) }}</dd>
+                    </div>
+                    <div v-if="detail.header.ccRecipients.length > 0" class="flex gap-1.5">
+                        <dt class="font-medium text-neutral-600 w-5 flex-shrink-0">{{ t('mail.cc') }}</dt>
+                        <dd class="break-all">{{ joinAddresses(detail.header.ccRecipients) }}</dd>
+                    </div>
+                    <div class="flex gap-1.5">
+                        <dt class="font-medium text-neutral-600 w-5 flex-shrink-0">{{ t('mail.date') }}</dt>
+                        <dd>{{ formatDate(detail.header.sentAt ?? detail.header.receivedAt) }}</dd>
+                    </div>
+                </dl>
+
+                <div class="flex flex-wrap items-center gap-2 pt-1">
+                    <MalioButton
+                        :label="t('mail.actions.createTask')"
+                        variant="primary"
+                        icon-name="material-symbols:add-task-outline"
+                        icon-position="left"
+                        :icon-size="14"
+                        @click="emit('createTask', detail.header.id)"
+                    />
+                    <MalioButton
+                        :label="t('mail.actions.linkTask')"
+                        variant="secondary"
+                        icon-name="material-symbols:link"
+                        icon-position="left"
+                        :icon-size="14"
+                        @click="emit('linkTask', detail.header.id)"
+                    />
+                    <MalioButton
+                        :label="detail.header.isRead ? t('mail.actions.markUnread') : t('mail.actions.markRead')"
+                        variant="tertiary"
+                        :icon-name="detail.header.isRead ? 'material-symbols:mark-email-unread-outline' : 'material-symbols:mark-email-read-outline'"
+                        icon-position="left"
+                        :icon-size="14"
+                        @click="handleMarkReadToggle"
+                    />
+                    <MalioButton
+                        :label="detail.header.isFlagged ? t('mail.actions.unflag') : t('mail.actions.flag')"
+                        variant="tertiary"
+                        :icon-name="detail.header.isFlagged ? 'material-symbols:star' : 'material-symbols:star-outline'"
+                        icon-position="left"
+                        :icon-size="14"
+                        @click="handleFlagToggle"
+                    />
+                </div>
+            </div>
+
+            <div class="flex-1 overflow-y-auto px-4 py-3">
+                <div
+                    v-if="!showImages && detail.bodyHtml"
+                    class="mb-3 flex items-center gap-3 rounded-md border border-amber-200 bg-amber-50 px-3 py-2 text-sm"
+                >
+                    <Icon name="material-symbols:image-outline" size="16" class="text-amber-500 flex-shrink-0" />
+                    <span class="flex-1 text-amber-700">
+                        {{ t('mail.remoteImagesBlocked') }}
+                    </span>
+                    <button
+                        type="button"
+                        class="text-xs font-medium text-amber-700 underline hover:text-amber-900 transition-colors"
+                        @click="showImages = true"
+                    >
+                        {{ t('mail.actions.showImages') }}
+                    </button>
+                </div>
+
+                <div
+                    v-if="detail.bodyHtml"
+                    class="prose prose-sm max-w-none text-neutral-800"
+                    v-html="sanitizedBody"
+                />
+
+                <pre
+                    v-else-if="detail.bodyText"
+                    class="whitespace-pre-wrap font-sans text-sm text-neutral-700"
+                >{{ detail.bodyText }}</pre>
+            </div>
+
+            <div
+                v-if="detail.attachments.length > 0"
+                class="flex-shrink-0 border-t border-neutral-200 px-4 py-3"
+            >
+                <p class="mb-2 text-xs font-semibold uppercase tracking-wide text-neutral-500">
+                    {{ t('mail.attachments') }} ({{ detail.attachments.length }})
+                </p>
+                <div class="flex flex-wrap gap-2">
+                    <button
+                        v-for="att in detail.attachments"
+                        :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)"
+                    >
+                        <Icon name="material-symbols:attach-file" 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>
+                    </button>
+                </div>
+            </div>
+        </template>
+    </div>
+</template>