diff --git a/src/frontend/public/locales/common/en-US.json b/src/frontend/public/locales/common/en-US.json
index 1327bc87..19a57672 100755
--- a/src/frontend/public/locales/common/en-US.json
+++ b/src/frontend/public/locales/common/en-US.json
@@ -634,6 +634,7 @@
   "Send and archive": "Send and archive",
   "Send and receive your messages in an instant.": "Send and receive your messages in an instant.",
   "Send Feedback": "Send Feedback",
+  "Sending is taking longer than expected. You can track your message in the Outbox.": "Sending is taking longer than expected. You can track your message in the Outbox.",
   "Sending message...": "Sending message...",
   "Sent": "Sent",
   "Sent by {{name}}": "Sent by {{name}}",
@@ -709,7 +710,6 @@
   "The forced signature will be the only one usable for new messages.": "The forced signature will be the only one usable for new messages.",
   "The mailbox \"{{mailbox}}\" currently has read-only access on this thread. To assign {{user}} to it, edit permissions must be granted to this mailbox.": "The mailbox \"{{mailbox}}\" currently has read-only access on this thread. To assign {{user}} to it, edit permissions must be granted to this mailbox.",
   "The message could not be sent.": "The message could not be sent.",
-  "The message could not be sent. Please try again later.": "The message could not be sent. Please try again later.",
   "The organizer marked this event as tentative.": "The organizer marked this event as tentative.",
   "The personal mailbox <strong>{{mailboxAddress}}</strong> has been created successfully.": "The personal mailbox <1>{{mailboxAddress}}</1> has been created successfully.",
   "The PST archive is unreadable: the file is corrupt or its internal structure is incomplete. Retrying will not help — please try to re-generate the archive.": "The PST archive is unreadable: the file is corrupt or its internal structure is incomplete. Retrying will not help — please try to re-generate the archive.",
diff --git a/src/frontend/public/locales/common/fr-FR.json b/src/frontend/public/locales/common/fr-FR.json
index 32427e66..3640a043 100755
--- a/src/frontend/public/locales/common/fr-FR.json
+++ b/src/frontend/public/locales/common/fr-FR.json
@@ -710,6 +710,7 @@
   "Send and archive": "Envoyer et archiver",
   "Send and receive your messages in an instant.": "Envoyez et recevez vos messages en un instant.",
   "Send Feedback": "Envoyer le message",
+  "Sending is taking longer than expected. You can track your message in the Outbox.": "L'envoi prend plus de temps que prévu. Vous pouvez suivre votre message dans la boîte d'envoi.",
   "Sending message...": "Envoi du message en cours...",
   "Sent": "Envoyés",
   "Sent by {{name}}": "Envoyé par {{name}}",
@@ -788,7 +789,6 @@
   "The forced signature will be the only one usable for new messages.": "La signature forcée sera la seule utilisable pour les nouveaux messages.",
   "The mailbox \"{{mailbox}}\" currently has read-only access on this thread. To assign {{user}} to it, edit permissions must be granted to this mailbox.": "La boîte « {{mailbox}} » n'a actuellement que les droits en lecture sur cette conversation. Pour y assigner {{user}}, les droits en édition doivent être accordés à cette boîte.",
   "The message could not be sent.": "Le message n'a pas pu être envoyé.",
-  "The message could not be sent. Please try again later.": "Le message n'a pas pu être envoyé. Veuillez réessayer plus tard.",
   "The organizer marked this event as tentative.": "L'organisateur a marqué cet événement comme provisoire.",
   "The personal mailbox <strong>{{mailboxAddress}}</strong> has been created successfully.": "L'adresse personnelle <strong>{{mailboxAddress}}</strong> a été créée avec succès.",
   "The PST archive is unreadable: the file is corrupt or its internal structure is incomplete. Retrying will not help — please try to re-generate the archive.": "L'archive PST est illisible : le fichier est corrompu ou sa structure interne est incomplète. Réessayer ne servira à rien — veuillez essayer de régénérer l'archive.",
diff --git a/src/frontend/src/features/forms/components/message-form/index.tsx b/src/frontend/src/features/forms/components/message-form/index.tsx
index 1ab639f9..f1570008 100644
--- a/src/frontend/src/features/forms/components/message-form/index.tsx
+++ b/src/frontend/src/features/forms/components/message-form/index.tsx
@@ -106,7 +106,7 @@ export const MessageForm = ({
     const autoSaveTimerRef = useRef<NodeJS.Timeout | null>(null);
     const saveDraftRef = useRef<() => void>(() => {});
     const quoteType: QuoteType | undefined = mode !== "new" ? (mode === "forward" ? "forward" : "reply") : undefined;
-    const { selectedMailbox, selectedThread, mailboxes, removeMessages, invalidateMailbox, invalidateThreadsStats, unselectThread, unpinThreads, pinThreads } = useMailboxContext();
+    const { selectedMailbox, selectedThread, mailboxes, removeMessages, patchMessages, invalidateMailbox, invalidateThreadsStats, unselectThread, unpinThreads, pinThreads } = useMailboxContext();
     const hideSubjectField = Boolean(draftMessage?.parent_id ?? parentMessage);
     // For replies/forwards, only allow sending from a mailbox that has access to the thread.
     const availableMailboxes = useMemo(() => {
@@ -287,8 +287,20 @@ export const MessageForm = ({
                 form.clearErrors();
                 toast.dismiss(DRAFT_TOAST_ID);
             },
-            onSuccess: async (response) => {
+            onSuccess: async (response, variables) => {
                 const data = (response as sendCreateResponse200).data;
+                // The backend un-drafts the message synchronously before queuing
+                // the SMTP task. Reflect that optimistically so the thread renders
+                // it as a sending message right away instead of keeping the draft
+                // form open until the background refetch lands.
+                const sentThreadId = draft?.thread_id ?? selectedThread?.id;
+                if (sentThreadId) {
+                    patchMessages(sentThreadId, (message) =>
+                        message.id === variables.data.messageId
+                            ? { ...message, is_draft: false }
+                            : message
+                    );
+                }
                 addQueuedMessage(data.task_id);
                 onSuccess?.();
             }
diff --git a/src/frontend/src/features/layouts/components/thread-view/components/message-reply-form/index.tsx b/src/frontend/src/features/layouts/components/thread-view/components/message-reply-form/index.tsx
index 8d14b39a..67095cba 100644
--- a/src/frontend/src/features/layouts/components/thread-view/components/message-reply-form/index.tsx
+++ b/src/frontend/src/features/layouts/components/thread-view/components/message-reply-form/index.tsx
@@ -17,10 +17,13 @@ const MessageReplyForm = ({ handleClose, message, mode }: MessageReplyFormProps)
                 draftMessage={message.is_draft ? message : undefined}
                 parentMessage={message.is_draft ? undefined : message}
                 mode={mode}
-                onSuccess={async () => {
-                    // Force refetch the messages query to avoid showing the draft message in the thread view
-                    await queryClient.refetchQueries({ queryKey: ["messages", message.thread_id] });
+                onSuccess={() => {
+                    // Close right away: MessageForm has optimistically un-drafted
+                    // the message, so the thread already shows it as sending.
                     handleClose();
+                    // Reconcile with the server state (delivery status, etc.) in
+                    // the background without blocking the form close.
+                    void queryClient.refetchQueries({ queryKey: ["messages", message.thread_id] });
                 }}
                 onClose={handleClose}
             />
diff --git a/src/frontend/src/features/layouts/components/thread-view/components/thread-message/_index.scss b/src/frontend/src/features/layouts/components/thread-view/components/thread-message/_index.scss
index eb670ecf..e10f2e09 100644
--- a/src/frontend/src/features/layouts/components/thread-view/components/thread-message/_index.scss
+++ b/src/frontend/src/features/layouts/components/thread-view/components/thread-message/_index.scss
@@ -224,8 +224,7 @@
     display: flex;
     justify-content: center;
     align-items: center;
-    height: 100%;
-    margin-block: var(--c--globals--spacings--base);
+    margin-bottom: var(--c--globals--spacings--base);
 }
 
 .thread-message__reply-form {
diff --git a/src/frontend/src/features/layouts/components/thread-view/components/thread-message/index.tsx b/src/frontend/src/features/layouts/components/thread-view/components/thread-message/index.tsx
index f8504c0d..f29afbe9 100644
--- a/src/frontend/src/features/layouts/components/thread-view/components/thread-message/index.tsx
+++ b/src/frontend/src/features/layouts/components/thread-view/components/thread-message/index.tsx
@@ -321,7 +321,12 @@ export const ThreadMessage = forwardRef<HTMLSpanElement, ThreadMessageProps>(
                         icon={<Icon name="update" type={IconType.OUTLINED} />}
                         type="warning"
                         fullWidth
-                        actions={canUpdateDeliveryStatus ? [
+                        // Only offer cancellation when there are recipients the
+                        // backend can actually transition (retry). A message still
+                        // being sent has pending recipients (delivery_status null),
+                        // which the banner reports but which cannot be cancelled —
+                        // showing the button there would POST an empty payload.
+                        actions={canUpdateDeliveryStatus && retryRecipients.length > 0 ? [
                             {
                                 label: t('Cancel those sendings'),
                                 onClick: handleCancelRetries,
diff --git a/src/frontend/src/features/providers/sent-box/queued-message.tsx b/src/frontend/src/features/providers/sent-box/queued-message.tsx
index 070daea7..e2be18c3 100644
--- a/src/frontend/src/features/providers/sent-box/queued-message.tsx
+++ b/src/frontend/src/features/providers/sent-box/queued-message.tsx
@@ -95,8 +95,17 @@ export const QueueMessage = ({ taskId, onSettled }: QueueMessageProps) => {
 
     useEffect(() => {
         if (hasTimedOut) {
+            // The send didn't fail: the backend already un-drafted the message and
+            // the SMTP task is still running. Reassure the user and point them to
+            // the Outbox rather than showing a misleading error. onSettled refreshes
+            // the stats so the Outbox folder reflects the pending message.
             toast.update(toastId, {
-                render: <ToasterItem type="error"><span>{t('The message could not be sent. Please try again later.')}</span></ToasterItem>,
+                render: (
+                    <ToasterItem type="warning">
+                        <span className="material-icons">schedule_send</span>
+                        <span>{t('Sending is taking longer than expected. You can track your message in the Outbox.')}</span>
+                    </ToasterItem>
+                ),
                 autoClose: QUEUED_MESSAGE_CLOSE_DELAY * 2,
             });
             onSettled?.();