diff --git a/lib/CompositionManager.php b/lib/CompositionManager.php
index f10c105..0f225ff 100644
--- a/lib/CompositionManager.php
+++ b/lib/CompositionManager.php
@@ -10,6 +10,7 @@ use KTXF\Mail\Object\AddressInterface;
 use KTXF\Mail\Object\MessagePart;
 use KTXF\Mail\Object\MessagePropertiesMutableInterface;
 use KTXF\Mail\Service\ServiceEntitySubmitInterface;
+use KTXF\Mail\Submission\EntitySubmitResult;
 use KTXF\Resource\Identifier\EntityIdentifierInterface;
 use KTXF\Resource\Identifier\ResourceIdentifier;
 use KTXF\Utile\UUID;
@@ -158,7 +159,7 @@ class CompositionManager {
         if ($sender['address'] === '' || !filter_var($sender['address'], FILTER_VALIDATE_EMAIL)) {
             $result['disposition'] = 'error';
             $result['error'] = [
-                'type' => 'invalid_sender',
+                'type' => 'composition_invalid_sender',
                 'message' => 'Invalid sender address',
             ];
             return $result;
@@ -171,15 +172,19 @@ class CompositionManager {
         if ($service === null || $service->getEnabled() === false) {
             return [
                 'disposition' => 'error',
-                'errorCode' => 'service_not_found',
-                'errorMessage' => "Service not found for sender '$senderAddress' or service is disabled",
+                'error' => [
+                    'type' => 'service_not_found',
+                    'message' => "Service not found for sender '$senderAddress' or service is disabled",
+                ],
             ];
         }
         if ($service instanceof ServiceEntitySubmitInterface === false) {
             return [
                 'disposition' => 'error',
-                'errorCode' => 'service_not_supported',
-                'errorMessage' => "Service '{$service->identifier()}' does not support entity submission",
+                'error' => [
+                    'type' => 'service_not_supported',
+                    'message' => "Service '{$service->identifier()}' does not support entity submission",
+                ],
             ];
         }
 
@@ -197,7 +202,21 @@ class CompositionManager {
 
         $sendResult = $service->entitySubmit($senderObject, $source, $properties);
 
-        return $sendResult->jsonSerialize();
+        if ($sendResult->disposition === EntitySubmitResult::DISPOSITION_ERROR) {
+            return [
+                'identifier' => $identifier,
+                'disposition' => 'error',
+                'error' => [
+                    'type' => 'service_submission_error',
+                    'message' => $sendResult->errorMessage ?? 'An unknown error occurred during submission',
+                ],
+            ];
+        }
+
+        return [
+            'identifier' => $identifier,
+            'disposition' => 'sent'
+        ];
     }
 
     private function buildMessageProperties(
diff --git a/src/components/MessageReader.vue b/src/components/MessageReader.vue
index 56f782e..3a11cb8 100644
--- a/src/components/MessageReader.vue
+++ b/src/components/MessageReader.vue
@@ -3,7 +3,7 @@ import { computed, ref, watch } from 'vue'
 import { useUser } from '@KTXC'
 import type { EntityObject, MessageObject } from '@MailManager/models'
 import { SecurityLevel } from '@/utile/emailSanitizer'
-import { useMailStore } from '@/stores/mailStore'
+import { useMailUiStore } from '@/stores/mailUiStore'
 import ReaderEmpty from './reader/ReaderEmpty.vue'
 import ReaderToolbar from './reader/ReaderToolbar.vue'
 import ReaderHeader from './reader/ReaderHeader.vue'
@@ -26,7 +26,7 @@ const emit = defineEmits<{
 
 // User settings
 const { getSetting } = useUser()
-const mailStore = useMailStore()
+const mailUiStore = useMailUiStore()
 
 // Per-message overrides
 const allowImages = ref(false)
@@ -101,7 +101,7 @@ const handleDownload = async (partIndex?: number) => {
     return
   }
 
-  await mailStore.downloadMessage(props.entity, partIndex)
+  await mailUiStore.downloadMessage(props.entity, partIndex)
 }
 
 const handleFlag = () => {
diff --git a/src/components/common/RecipientDetails.vue b/src/components/common/RecipientDetails.vue
index 54282e9..ad82376 100644
--- a/src/components/common/RecipientDetails.vue
+++ b/src/components/common/RecipientDetails.vue
@@ -1,6 +1,5 @@
 <script setup lang="ts">
 import { computed } from 'vue'
-import { useSnackbar } from '@KTXC'
 import type { MessageAddressInterface } from '@MailManager/types/message'
 import { useMailUiStore } from '@/stores/mailUiStore'
 import { ComposerMode } from '@/types/composer'
@@ -17,7 +16,6 @@ const emit = defineEmits<{
 }>()
 
 const mailUiStore = useMailUiStore()
-const { showSnackbar } = useSnackbar()
 
 const recipientLabel = computed(() => props.address?.label?.trim() || '')
 const recipientAddress = computed(() => props.address?.address?.trim() || '')
@@ -32,7 +30,7 @@ const formattedAddress = computed(() => {
 const hasEmail = computed(() => recipientAddress.value.length > 0)
 
 const showCopyResult = (message: string, color: 'success' | 'error') => {
-  showSnackbar({ message, color })
+  mailUiStore.notify(message, color)
 }
 
 const copy = async (value: string, label: string) => {
diff --git a/src/pages/MailPage.vue b/src/pages/MailPage.vue
index 87e6259..e79b974 100644
--- a/src/pages/MailPage.vue
+++ b/src/pages/MailPage.vue
@@ -156,12 +156,12 @@ const handleMessageComposeForward = (message: EntityObject) => mailUiStore.openC
 
 const handleMessageComposeClose = () => mailUiStore.closeComposer()
 
-const handleMessageFlag = (message: EntityObject, flag: string, value: boolean) => {
-  mailStore.flagMessages([message.identifier], { [flag]: value })
+const handleMessageFlag = async (message: EntityObject, flag: string, value: boolean) => {
+  await mailUiStore.flagMessage(message, flag, value)
 }
 
-const handleMessageDelete = (message: EntityObject) => {
-  mailStore.deleteMessages([message.identifier])
+const handleMessageDelete = async (message: EntityObject) => {
+  await mailUiStore.deleteMessages([message.identifier])
 }
 
 const handleMessageMove = (message: EntityObject) => mailUiStore.openMoveMessagesDialog(message)
diff --git a/src/stores/mailCompositionStore.ts b/src/stores/mailCompositionStore.ts
index 87ad5fa..a38c641 100644
--- a/src/stores/mailCompositionStore.ts
+++ b/src/stores/mailCompositionStore.ts
@@ -14,11 +14,11 @@ import type {
 import { ComposerMode } from '@/types/composer'
 import type { ComposerDraft, ComposerDraftAttachment, ComposerDraftMessage, ComposerSenderIdentity } from '@/types/composer'
 import { EntityObject, MessageAddressObject, ServiceObject } from '@MailManager/models'
-import type { ServiceIdentifier } from '@MailManager/services'
 
 export const useMailCompositionStore = defineStore('mailCompositionStore', () => {
   const servicesStore = useServicesStore()
   const mailUiStore = useMailUiStore()
+  
   const activeDraft = ref<ComposerDraft | null>(null)
   const saving = ref(false)
 
@@ -206,7 +206,7 @@ export const useMailCompositionStore = defineStore('mailCompositionStore', () =>
     }
     
     try {
-      await compositionService.send({ 
+      const response = await compositionService.send({ 
         identifier: activeDraft.value.identifier,
         revision: activeDraft.value.revision,
         sender: {
@@ -218,7 +218,16 @@ export const useMailCompositionStore = defineStore('mailCompositionStore', () =>
         message: activeDraft.value.message,
         attachments: activeDraft.value.attachments,
       })
+
+      if (response.disposition === 'error') {
+        console.error('[Mail][Composer] Failed to send message:', response.error)
+        mailUiStore.notify(`Failed to send message: ${response.error?.message || 'Unknown error'}`, 'error')
+        return
+      }
+
       activeDraft.value = null
+      mailUiStore.notify('Message sent successfully', 'success')
+      mailUiStore.closeComposer()
     } catch (error) {
       console.error('[Mail][Composer] Failed to send draft:', error)
       throw error
diff --git a/src/stores/mailStore.ts b/src/stores/mailStore.ts
index 2b57b7c..0173efc 100644
--- a/src/stores/mailStore.ts
+++ b/src/stores/mailStore.ts
@@ -4,7 +4,6 @@ import { useCollectionsStore } from '@MailManager/stores/collectionsStore'
 import { useEntitiesStore } from '@MailManager/stores/entitiesStore'
 import { useServicesStore } from '@MailManager/stores/servicesStore'
 import { useMailSync } from '@MailManager/composables/useMailSync'
-import { useSnackbar } from '@KTXC'
 import type { ServiceIdentifier, CollectionIdentifier, EntityIdentifier } from '@MailManager/types/common'
 import type { EntityTransmitRequest } from '@MailManager/types/entity'
 import type { MessageAddressInterface, MessageInterface, MessagePartInterface } from '@MailManager/types/message'
@@ -26,7 +25,6 @@ export const useMailStore = defineStore('mailStore', () => {
   const servicesStore = useServicesStore()
   const collectionsStore = useCollectionsStore()
   const entitiesStore = useEntitiesStore()
-  const { showSnackbar } = useSnackbar()
 
   // Background mail sync
   const mailSyncController = useMailSync({
@@ -398,13 +396,10 @@ export const useMailStore = defineStore('mailStore', () => {
         }
       }
 
-      notify('Message sent', 'success')
       resetComposerState()
       return response
     } catch (error) {
-      const messageText = error instanceof Error ? error.message : 'Failed to send message'
       console.error('[Mail][Operations] Failed to send message:', error)
-      notify(messageText, 'error')
       throw error
     } finally {
       composerSending.value = false
@@ -428,11 +423,6 @@ export const useMailStore = defineStore('mailStore', () => {
       parentFolder?.identifier,
     )
 
-    notify(
-      `Folder "${newFolder.properties.label || properties.label}" created`,
-      'success',
-    )
-
     return newFolder
   }
 
@@ -448,11 +438,6 @@ export const useMailStore = defineStore('mailStore', () => {
       selectedFolder.value = updatedFolder
     }
 
-    notify(
-      `Folder "${folder.properties.label || String(folder.identifier)}" renamed to "${updatedFolder.properties.label || properties.label}"`,
-      'success',
-    )
-
     return updatedFolder
   }
 
@@ -463,11 +448,6 @@ export const useMailStore = defineStore('mailStore', () => {
       selectedFolder.value = movedFolder
     }
 
-    notify(
-      `Folder "${source.properties.label || String(source.identifier)}" moved to "${target.properties.label || String(target.identifier)}"`,
-      'success',
-    )
-
     return movedFolder
   }
 
@@ -478,81 +458,38 @@ export const useMailStore = defineStore('mailStore', () => {
       await selectFolder(null)
     }
 
-    notify(
-      `Folder "${folder.properties.label || String(folder.identifier)}" deleted`,
-      'success',
-    )
-
     return deletedFolder
   }
 
   async function deleteMessages(entityIdentifiers: EntityIdentifier[]) {
     if (entityIdentifiers.length === 0) {
-      return
+      return null
     }
 
     loading.value = true
 
     try {
-      const { successes, failures } = await entitiesStore.delete(entityIdentifiers)
-
-      if (failures.length === 0) {
-        notify(
-          successes.length === 1 ? 'Message deleted' : `${successes.length} messages deleted`,
-          'success',
-        )
-      } 
-      
-      if (failures.length > 0) {
-        notify(
-          successes.length === 0
-            ? `Delete failed for ${failures.length === 1 ? '1 message' : `${failures.length} messages`}`
-            : `Deleted ${successes.length} ${successes.length === 1 ? 'message' : 'messages'}. ${failures.length} failed.`,
-          successes.length === 0 ? 'error' : 'warning',
-        )
-      }
+      return await entitiesStore.delete(entityIdentifiers)
     } catch (error) {
-      const messageText = error instanceof Error ? error.message : 'Failed to delete messages'
       console.error('[Mail][Operations] Failed to delete messages:', error)
-      notify(messageText, 'error')
       throw error
     } finally {
       loading.value = false
     }
   }
 
-  async function flagMessages(entityIdentifiers: EntityIdentifier[], flags: Partial<MessageInterface['flags']>, options: { notify?: boolean } = {}) {
+  async function flagMessages(entityIdentifiers: EntityIdentifier[], flags: Partial<NonNullable<MessageInterface['flags']>>) {
     if (entityIdentifiers.length === 0) {
-      return
+      return null
     }
 
-    const shouldNotify = options.notify ?? true
-
     try {
       const patch = entitiesStore.fresh().properties
       patch.flags = flags
 
-      const { successes, failures } = await entitiesStore.patch(patch, entityIdentifiers)
-
-      if (shouldNotify && successes.length > 0) {
-        notify(
-          successes.length === 1 ? 'Message updated' : `${successes.length} messages updated`,
-          'success',
-        )
-      }
-
-      if (shouldNotify && failures.length > 0) {
-        notify(
-          successes.length === 0
-            ? `Update failed for ${failures.length === 1 ? '1 message' : `${failures.length} messages`}`
-            : `Updated ${successes.length} ${successes.length === 1 ? 'message' : 'messages'}. ${failures.length} failed.`,
-          successes.length === 0 ? 'error' : 'warning',
-        )
-      }
+      return await entitiesStore.patch(patch, entityIdentifiers)
     } catch (error) {
-      const messageText = error instanceof Error ? error.message : 'Failed to update messages'
       console.error('[Mail][Operations] Failed to update messages:', error)
-      notify(messageText, 'error')
       throw error
     }
   }
@@ -592,7 +529,7 @@ export const useMailStore = defineStore('mailStore', () => {
     )
 
     if (movableIdentifiers.length === 0) {
-      return
+      return null
     }
 
     loading.value = true
@@ -600,29 +537,13 @@ export const useMailStore = defineStore('mailStore', () => {
     try {
       const { successes, failures } = await entitiesStore.move(target.identifier, movableIdentifiers)
 
-      if (failures.length === 0) {
-        notify(
-          successes.length === 1 ? 'Message moved' : `${successes.length} messages moved`,
-          'success',
-        )
-      } 
-      
-      if (failures.length > 0) {
-        notify(
-          successes.length === 0
-            ? `Move failed for ${failures.length === 1 ? '1 message' : `${failures.length} messages`}`
-            : `Moved ${successes.length} ${successes.length === 1 ? 'message' : 'messages'}. ${failures.length} failed.`,
-          successes.length === 0 ? 'error' : 'warning',
-        )
-      }
-
       // update source collections to reflect moved messages
       sourceCollections.push(target.identifier)
       await collectionsStore.fetch(sourceCollections)
+
+      return { successes, failures }
     } catch (error) {
-      const messageText = error instanceof Error ? error.message : 'Failed to move messages'
       console.error('[Mail][Operations] Failed to move messages:', error)
-      notify(messageText, 'error')
       throw error
     } finally {
       loading.value = false
@@ -640,26 +561,16 @@ export const useMailStore = defineStore('mailStore', () => {
     try {
       await entitiesStore.download(target, part)
     } catch (error) {
-      const messageText = error instanceof Error
-        ? error.message
-        : index === undefined
-          ? 'Failed to download message'
-          : 'Failed to download attachment'
       console.error(
         index === undefined
           ? '[Mail][Operations] Failed to download message:'
           : '[Mail][Operations] Failed to download attachment:',
         error,
       )
-      notify(messageText, 'error')
       throw error
     }
   }
 
-  function notify(message: string, color: 'success' | 'error' | 'info' | 'warning' = 'success') {
-    showSnackbar({ message, color })
-  }
-
   // ── Exports ───────────────────────────────────────────────────────────────
 
   return {
@@ -698,7 +609,6 @@ export const useMailStore = defineStore('mailStore', () => {
     downloadMessage,
     moveFolder,
     renameFolder,
-    notify,
     isServiceFolderLoading,
     hasServiceFoldersLoaded,
     getServiceFolderError,
diff --git a/src/stores/mailUiStore.ts b/src/stores/mailUiStore.ts
index 59c7b78..3cdd25e 100644
--- a/src/stores/mailUiStore.ts
+++ b/src/stores/mailUiStore.ts
@@ -7,12 +7,15 @@ import { ComposerMode } from '@/types/composer'
 import type { ServiceIdentifier, EntityIdentifier } from '@MailManager/types/common'
 import { EntityObject, type ServiceObject } from '@MailManager/models'
 import type { CollectionObject } from '@MailManager/models/collection'
+import type { MessageInterface } from '@MailManager/types/message'
 import type { MessageAddressInterface } from '@MailManager/types/message'
+import { useSnackbar } from '@KTXC'
 
 export const useMailUiStore = defineStore('mailUiStore', () => {
   const collectionsStore = useCollectionsStore()
   const mailStore = useMailStore()
   const mailSettingsStore = useMailSettingsStore()
+  const { showSnackbar } = useSnackbar()
 
   const sidebarVisible = ref(true)
   const settingsDialogVisible = ref(false)
@@ -112,6 +115,18 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
     },
   )
 
+  async function initialize() {
+    await mailStore.initialize()
+
+    if (!selectedFolder.value) {
+      const inbox = mailStore.findFoldersByRole('inbox')[0] ?? null
+
+      if (inbox) {
+        await selectFolder(inbox)
+      }
+    }
+  }
+
   function sidebarToggle() {
     sidebarVisible.value = !sidebarVisible.value
   }
@@ -128,6 +143,52 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
     settingsDialogVisible.value = false
   }
 
+  function notify(message: string, color: 'success' | 'error' | 'info' | 'warning' = 'success') {
+    showSnackbar({ message, color })
+  }
+
+  function notifyDeleteMessagesResult(successes: number, failures: number) {
+    if (failures === 0) {
+      notify(successes === 1 ? 'Message deleted' : `${successes} messages deleted`, 'success')
+      return
+    }
+
+    notify(
+      successes === 0
+        ? `Delete failed for ${failures === 1 ? '1 message' : `${failures} messages`}`
+        : `Deleted ${successes} ${successes === 1 ? 'message' : 'messages'}. ${failures} failed.`,
+      successes === 0 ? 'error' : 'warning',
+    )
+  }
+
+  function notifyFlagMessagesResult(successes: number, failures: number) {
+    if (failures === 0) {
+      notify(successes === 1 ? 'Message updated' : `${successes} messages updated`, 'success')
+      return
+    }
+
+    notify(
+      successes === 0
+        ? `Update failed for ${failures === 1 ? '1 message' : `${failures} messages`}`
+        : `Updated ${successes} ${successes === 1 ? 'message' : 'messages'}. ${failures} failed.`,
+      successes === 0 ? 'error' : 'warning',
+    )
+  }
+
+  function notifyMoveMessagesResult(successes: number, failures: number) {
+    if (failures === 0) {
+      notify(successes === 1 ? 'Message moved' : `${successes} messages moved`, 'success')
+      return
+    }
+
+    notify(
+      successes === 0
+        ? `Move failed for ${failures === 1 ? '1 message' : `${failures} messages`}`
+        : `Moved ${successes} ${successes === 1 ? 'message' : 'messages'}. ${failures} failed.`,
+      successes === 0 ? 'error' : 'warning',
+    )
+  }
+
   function _sameCollection(left: CollectionObject | null | undefined, right: CollectionObject | null | undefined): boolean {
     if (!left || !right) {
       return false
@@ -138,18 +199,6 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
       String(left.identifier) === String(right.identifier)
   }
 
-  async function initialize() {
-    await mailStore.initialize()
-
-    if (!selectedFolder.value) {
-      const inbox = mailStore.findFoldersByRole('inbox')[0] ?? null
-
-      if (inbox) {
-        await selectFolder(inbox)
-      }
-    }
-  }
-
   async function selectFolder(folder: CollectionObject | null) {
     closeComposer()
     messageSelectionModeDeactivate()
@@ -200,7 +249,7 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
   async function completeMessageRead(identifier: EntityIdentifier) {
     try {
       if (selectedMessage.value && selectedMessage.value.identifier === identifier && selectedMessage.value.properties.isRead === false) {
-        await mailStore.flagMessages([selectedMessage.value.identifier], { read: true }, { notify: false })
+        await flagMessages([selectedMessage.value.identifier], { read: true }, { notify: false })
       }
     } catch (error) {
       console.error('[Mail][UI] Failed to auto-mark message as read:', error)
@@ -237,6 +286,7 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
 
     try {
       const folder = await mailStore.createFolder(service, label, createFolderDialogParent.value)
+      notify(`Folder "${folder.properties.label || label.trim()}" created`, 'success')
       closeCreateFolderDialog()
       return folder
     } catch (error) {
@@ -281,6 +331,11 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
         selectedFolder.value = updatedFolder
       }
 
+      notify(
+        `Folder "${folder.properties.label || String(folder.identifier)}" renamed to "${updatedFolder.properties.label || label.trim()}"`,
+        'success',
+      )
+
       closeRenameFolderDialog()
       return updatedFolder
     } catch (error) {
@@ -317,6 +372,11 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
       selectedFolder.value = movedFolder
     }
 
+    notify(
+      `Folder "${source.properties.label || String(source.identifier)}" moved to "${target.properties.label || String(target.identifier)}"`,
+      'success',
+    )
+
     closeMoveFolderDialog()
     return movedFolder
   }
@@ -353,9 +413,10 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
 
       if (_sameCollection(selectedFolder.value, folder)) {
         selectFolder(null)
-        
       }
 
+      notify(`Folder "${folder.properties.label || String(folder.identifier)}" deleted`, 'success')
+
       closeDeleteFolderDialog()
       return deleted
     } catch (error) {
@@ -556,21 +617,99 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
   }
 
   async function confirmMoveMessages(targetIdentifier: Parameters<typeof mailStore.moveMessages>[0]) {
-    await mailStore.moveMessages(targetIdentifier, moveMessagesDialogCandidates.value ?? [])
+    await moveMessages(targetIdentifier, moveMessagesDialogCandidates.value ?? [])
     messageSelectionModeDeactivate()
     closeMoveMessagesDialog()
   }
 
   async function deleteSelectedMessages() {
-    await mailStore.deleteMessages([...selectionList.value])
+    await deleteMessages([...selectionList.value])
     messageSelectionModeDeactivate()
   }
 
   async function flagSelectedMessages(flag: string, value: boolean) {
-    await mailStore.flagMessages([...selectionList.value],  { [flag]: value })
+    await flagMessages([...selectionList.value], { [flag]: value })
     messageSelectionModeDeactivate()
   }
 
+  async function deleteMessages(entityIdentifiers: EntityIdentifier[]) {
+    try {
+      const result = await mailStore.deleteMessages(entityIdentifiers)
+
+      if (!result) {
+        return null
+      }
+
+      notifyDeleteMessagesResult(result.successes.length, result.failures.length)
+      return result
+    } catch (error) {
+      const messageText = error instanceof Error ? error.message : 'Failed to delete messages'
+      notify(messageText, 'error')
+      throw error
+    }
+  }
+
+  async function flagMessages(
+    entityIdentifiers: EntityIdentifier[],
+    flags: Partial<NonNullable<MessageInterface['flags']>>,
+    options: { notify?: boolean } = {},
+  ) {
+    try {
+      const result = await mailStore.flagMessages(entityIdentifiers, flags)
+
+      if (!result) {
+        return null
+      }
+
+      if (options.notify ?? true) {
+        notifyFlagMessagesResult(result.successes.length, result.failures.length)
+      }
+
+      return result
+    } catch (error) {
+      const messageText = error instanceof Error ? error.message : 'Failed to update messages'
+      if (options.notify ?? true) {
+        notify(messageText, 'error')
+      }
+      throw error
+    }
+  }
+
+  async function flagMessage(entity: EntityObject, flag: string, value: boolean) {
+    return await flagMessages([entity.identifier], { [flag]: value })
+  }
+
+  async function moveMessages(target: CollectionObject, entityIdentifiers: EntityIdentifier[]) {
+    try {
+      const result = await mailStore.moveMessages(target, entityIdentifiers)
+
+      if (!result) {
+        return null
+      }
+
+      notifyMoveMessagesResult(result.successes.length, result.failures.length)
+      return result
+    } catch (error) {
+      const messageText = error instanceof Error ? error.message : 'Failed to move messages'
+      notify(messageText, 'error')
+      throw error
+    }
+  }
+
+  async function downloadMessage(entity: EntityObject, index?: number) {
+    try {
+      await mailStore.downloadMessage(entity, index)
+    } catch (error) {
+      const messageText = error instanceof Error
+        ? error.message
+        : index === undefined
+          ? 'Failed to download message'
+          : 'Failed to download attachment'
+      notify(messageText, 'error')
+      throw error
+    }
+  }
+
   return {
     sidebarVisible,
     settingsDialogVisible,
@@ -605,14 +744,20 @@ export const useMailUiStore = defineStore('mailUiStore', () => {
     deleteFolderDialogFolder,
     deleteFolderDialogLoading,
     deleteFolderDialogError,
+    initialize,
     sidebarToggle,
     sidebarHide,
     settingsOpen,
     settingsClose,
-    initialize,
+    notify,
     selectFolder,
     openComposer,
     closeComposer,
+    deleteMessages,
+    flagMessages,
+    flagMessage,
+    moveMessages,
+    downloadMessage,
     messageSelectionModeActivate,
     messageSelectionModeDeactivate,
     messageSelectionToggleOne,
diff --git a/src/types/composition.ts b/src/types/composition.ts
index c352caa..b3e38e5 100644
--- a/src/types/composition.ts
+++ b/src/types/composition.ts
@@ -63,7 +63,11 @@ export interface CompositionDiscardRequest {
 
 export interface CompositionDiscardResponse {
   identifier: string
-  disposition: boolean
+  disposition: 'discarded' | 'error'
+  error?: {
+    type: string
+    message: string
+  }
 }
 
 export interface CompositionSendRequest {
@@ -76,7 +80,11 @@ export interface CompositionSendRequest {
 
 export interface CompositionSendResponse {
   identifier: string
-  disposition: boolean
+  disposition: 'sent' | 'error'
+  error?: {
+    type: string
+    message: string
+  }
 }
 
 export interface CompositionAttachmentAddRequest {