diff --git a/lib/Controllers/CompositionController.php b/lib/Controllers/CompositionController.php
index 073750a..267c928 100644
--- a/lib/Controllers/CompositionController.php
+++ b/lib/Controllers/CompositionController.php
@@ -80,8 +80,8 @@ final class CompositionController extends ControllerAbstract {
         if (!isset($data['action']) || !is_string($data['action'])) {
             throw new InvalidArgumentException('Invalid parameter: action must be a string');
         }
-        if (!in_array($data['action'], ['fresh', 'reply', 'forward'], true)) {
-            throw new InvalidArgumentException('Invalid parameter: action must be one of fresh, reply, forward');
+        if (!in_array($data['action'], ['fresh', 'reply', 'replyAll', 'forward'], true)) {
+            throw new InvalidArgumentException('Invalid parameter: action must be one of fresh, reply, replyAll, forward');
         }
         if (!isset($data['sender']) || !is_array($data['sender'])) {
             throw new InvalidArgumentException('Invalid parameter: sender must be an array');
@@ -89,8 +89,8 @@ final class CompositionController extends ControllerAbstract {
         if (!isset($data['message']) || !is_array($data['message'])) {
             throw new InvalidArgumentException('Invalid parameter: message must be an array');
         }
-        if (($data['action'] === 'reply' || $data['action'] === 'forward') && (!isset($data['source']) || !is_string($data['source']) || $data['source'] === '')) {
-            throw new InvalidArgumentException('Invalid parameter: source must be a non-empty string for reply or forward action');
+        if (($data['action'] === 'reply' || $data['action'] === 'replyAll' || $data['action'] === 'forward') && (!isset($data['source']) || !is_string($data['source']) || $data['source'] === '')) {
+            throw new InvalidArgumentException('Invalid parameter: source must be a non-empty string for reply, replyAll, or forward action');
         }
 
         return $this->compositionManager->stage($tenantId, $userId, $data['identifier'], $data['action'], $data['sender'], $data['message'], $data['source'] ?? null);
diff --git a/src/components/MessageReader.vue b/src/components/MessageReader.vue
index 0467ffc..cb44019 100644
--- a/src/components/MessageReader.vue
+++ b/src/components/MessageReader.vue
@@ -19,6 +19,7 @@ const props = defineProps<{
 // Emits
 const emit = defineEmits<{
   reply: [entity: EntityObject]
+  replyAll: [entity: EntityObject]
   forward: [entity: EntityObject]
   move: [entity: EntityObject]
   delete: [entity: EntityObject]
@@ -107,6 +108,12 @@ const handleReply = () => {
   }
 }
 
+const handleReplyAll = () => {
+  if (props.entity) {
+    emit('replyAll', props.entity)
+  }
+}
+
 const handleForward = () => {
   if (props.entity) {
     emit('forward', props.entity)
@@ -176,6 +183,7 @@ const handleViewerDownload = (item: MediaViewerItem) => {
         :security-level="effectiveSecurityLevel"
         :is-security-overridden="overrideSecurityLevel !== null"
         @reply="handleReply"
+        @reply-all="handleReplyAll"
         @forward="handleForward"
         @move="handleMove"
         @delete="handleDelete"
diff --git a/src/components/composer/ComposerToolbar.vue b/src/components/composer/ComposerToolbar.vue
index 1279639..6732080 100644
--- a/src/components/composer/ComposerToolbar.vue
+++ b/src/components/composer/ComposerToolbar.vue
@@ -30,7 +30,7 @@ defineEmits<{
     </v-btn>
 
     <v-toolbar-title>
-      {{ mode === ComposerMode.Reply ? 'Reply' : mode === ComposerMode.Forward ? 'Forward' : 'New Message' }}
+      {{ mode === ComposerMode.Reply ? 'Reply' : mode === ComposerMode.ReplyAll ? 'Reply All' : mode === ComposerMode.Forward ? 'Forward' : 'New Message' }}
     </v-toolbar-title>
 
     <v-spacer />
diff --git a/src/components/reader/ReaderToolbar.vue b/src/components/reader/ReaderToolbar.vue
index 73ad720..39fa816 100644
--- a/src/components/reader/ReaderToolbar.vue
+++ b/src/components/reader/ReaderToolbar.vue
@@ -13,6 +13,7 @@ const props = defineProps<Props>()
 
 const emit = defineEmits<{
   reply: []
+  replyAll: []
   forward: []
   move: []
   delete: []
@@ -47,7 +48,7 @@ const currentSecurityLevel = computed(() => {
     <v-btn
       icon="mdi-reply-all"
       variant="text"
-      @click="emit('reply')"
+      @click="emit('replyAll')"
     >
       <v-icon>mdi-reply-all</v-icon>
       <v-tooltip activator="parent" location="bottom">Reply All</v-tooltip>
diff --git a/src/pages/Main.vue b/src/pages/Main.vue
index 454cb5d..b7cbb8f 100644
--- a/src/pages/Main.vue
+++ b/src/pages/Main.vue
@@ -167,6 +167,8 @@ const handleMessageComposeFresh = () => mailUiStore.openComposer()
 
 const handleMessageComposeReply = (message: EntityObject) => mailUiStore.openComposer(message, ComposerMode.Reply)
 
+const handleMessageComposeReplyAll = (message: EntityObject) => mailUiStore.openComposer(message, ComposerMode.ReplyAll)
+
 const handleMessageComposeForward = (message: EntityObject) => mailUiStore.openComposer(message, ComposerMode.Forward)
 
 const handleMessageComposeClose = () => mailUiStore.closeComposer()
@@ -339,6 +341,7 @@ const handleMessageSelectionDelete = () => mailUiStore.deleteSelectedMessages()
               :entity="selectedMessage"
               @compose="handleMessageComposeFresh"
               @reply="handleMessageComposeReply"
+              @reply-all="handleMessageComposeReplyAll"
               @forward="handleMessageComposeForward"
               @move="handleMessageMove"
               @delete="handleMessageDelete"
diff --git a/src/stores/mailCompositionStore.ts b/src/stores/mailCompositionStore.ts
index 718a34a..e09ed3e 100644
--- a/src/stores/mailCompositionStore.ts
+++ b/src/stores/mailCompositionStore.ts
@@ -118,7 +118,8 @@ export const useMailCompositionStore = defineStore('mailCompositionStore', () =>
       return
     }
 
-    activeDraft.value = buildDraft(mode, sender, source)
+    const ownAddresses = senderIdentities.value.map(identity => identity.address)
+    activeDraft.value = buildDraft(mode, sender, source, ownAddresses)
     activeDraft.value.action = mode
 
     stageDraft()
@@ -558,9 +559,9 @@ export const useMailCompositionStore = defineStore('mailCompositionStore', () =>
   }
 })
 
-function buildDraft(mode: ComposerMode, sender: ComposerSenderIdentity, source?: EntityObject | MessageAddressObject | null): ComposerDraft {
+function buildDraft(mode: ComposerMode, sender: ComposerSenderIdentity, source: EntityObject | MessageAddressObject | null | undefined, ownAddresses: string[]): ComposerDraft {
   const composition = createIdentifier()
-  const freshMessage = buildMessage(mode, source)
+  const freshMessage = buildMessage(mode, source, ownAddresses)
   const freshAttachments = buildAttachments(composition, mode, source)
   const sourceIdentifier = source instanceof EntityObject ? source.identifier : null
   return {
@@ -576,7 +577,7 @@ function buildDraft(mode: ComposerMode, sender: ComposerSenderIdentity, source?:
   }
 }
 
-function buildMessage(mode: ComposerMode, source: EntityObject | MessageAddressObject | null | undefined): ComposerDraftMessage {
+function buildMessage(mode: ComposerMode, source: EntityObject | MessageAddressObject | null | undefined, ownAddresses: string[] = []): ComposerDraftMessage {
   
   if (!source) {
     return emptyMessage()
@@ -603,12 +604,28 @@ function buildMessage(mode: ComposerMode, source: EntityObject | MessageAddressO
   const sentAt = sourceMessage.sent || source.created || ''
   const sentLabel = sentAt ? new Date(sentAt).toLocaleString() : 'an unknown time'
 
-  if (mode === ComposerMode.Reply) {
+  if (mode === ComposerMode.Reply || mode === ComposerMode.ReplyAll) {
     const replyToAddr = sourceMessage.replyTo?.[0] ?? sourceMessage.from ?? null
     const replyToAddress = replyToAddr?.address || ''
+    const to: MessageAddressInterface[] = replyToAddress ? [{ address: replyToAddress, label: replyToAddr?.label }] : []
+
+    let cc: MessageAddressInterface[] = []
+    if (mode === ComposerMode.ReplyAll) {
+      const excluded = new Set([replyToAddress.toLowerCase(), ...ownAddresses.map(addr => addr.toLowerCase())])
+      const seen = new Set<string>()
+      cc = [...(sourceMessage.to || []), ...(sourceMessage.cc || [])].filter(recipient => {
+        const address = recipient.address?.toLowerCase() || ''
+        if (!address || excluded.has(address) || seen.has(address)) {
+          return false
+        }
+        seen.add(address)
+        return true
+      })
+    }
+
     return {
-      to: replyToAddress ? [{ address: replyToAddress, label: replyToAddr?.label }] : [],
-      cc: [],
+      to,
+      cc,
       bcc: [],
       subject: /^Re:/i.test(originalSubject) ? originalSubject : `Re: ${originalSubject}`,
       body: {
@@ -631,7 +648,7 @@ function buildMessage(mode: ComposerMode, source: EntityObject | MessageAddressO
 }
 
 function buildAttachments(composition: string, mode: ComposerMode, source?: EntityObject | MessageAddressObject | null): Record<string, ComposerDraftAttachment> {
-  if (mode === ComposerMode.Fresh || mode === ComposerMode.Reply || !(source instanceof EntityObject)) {
+  if (mode === ComposerMode.Fresh || mode === ComposerMode.Reply || mode === ComposerMode.ReplyAll || !(source instanceof EntityObject)) {
     return {}
   }
 
diff --git a/src/types/composer.ts b/src/types/composer.ts
index 2e8953f..8df36e4 100644
--- a/src/types/composer.ts
+++ b/src/types/composer.ts
@@ -5,6 +5,7 @@ import type { MessageAddressInterface } from "@MailManager/types/message"
 export enum ComposerMode {
   Fresh = 'fresh',
   Reply = 'reply',
+  ReplyAll = 'replyAll',
   Forward = 'forward',
 }