diff --git a/lib/demo/demo-client.ts b/lib/demo/demo-client.ts
index 8238018e..ea0b4765 100644
--- a/lib/demo/demo-client.ts
+++ b/lib/demo/demo-client.ts
@@ -329,7 +329,7 @@ export class DemoJMAPClient implements IJMAPClient {
     this.recalcMailboxCounts();
   }
 
-  async emptyMailbox(mailboxId: string): Promise<number> {
+  async emptyMailbox(mailboxId: string, _accountId?: string): Promise<number> {
     const before = this.data.emails.length;
     this.data.emails = this.data.emails.filter(e => !e.mailboxIds[mailboxId]);
     const removed = before - this.data.emails.length;
diff --git a/lib/jmap/client-interface.ts b/lib/jmap/client-interface.ts
index f657cca9..abfad8eb 100644
--- a/lib/jmap/client-interface.ts
+++ b/lib/jmap/client-interface.ts
@@ -109,7 +109,7 @@ export interface IJMAPClient {
     accountId?: string,
   ): Promise<void>;
   moveEmail(emailId: string, toMailboxId: string, accountId?: string): Promise<void>;
-  emptyMailbox(mailboxId: string): Promise<number>;
+  emptyMailbox(mailboxId: string, accountId?: string): Promise<number>;
   markMailboxAsRead(mailboxId: string, accountId?: string): Promise<number>;
   markAllAsRead(excludeMailboxIds?: string[], accountId?: string): Promise<number>;
   markAsSpam(emailId: string, accountId?: string, markAsRead?: boolean): Promise<void>;
diff --git a/lib/jmap/client.ts b/lib/jmap/client.ts
index 54b565ed..cd66cf6c 100644
--- a/lib/jmap/client.ts
+++ b/lib/jmap/client.ts
@@ -1445,19 +1445,20 @@ export class JMAPClient implements IJMAPClient {
     }
   }
 
-  async emptyMailbox(mailboxId: string): Promise<number> {
+  async emptyMailbox(mailboxId: string, accountId?: string): Promise<number> {
+    const targetAccountId = accountId || this.accountId;
     let totalDestroyed = 0;
     let hasMore = true;
 
     while (hasMore) {
       const response = await this.request([
         ["Email/query", {
-          accountId: this.accountId,
+          accountId: targetAccountId,
           filter: { inMailbox: mailboxId },
           limit: 500,
         }, "0"],
         ["Email/set", {
-          accountId: this.accountId,
+          accountId: targetAccountId,
           "#destroy": { resultOf: "0", name: "Email/query", path: "/ids" },
         }, "1"],
       ]);
diff --git a/stores/email-store.ts b/stores/email-store.ts
index 8e8a3d0b..ab746e70 100644
--- a/stores/email-store.ts
+++ b/stores/email-store.ts
@@ -2438,7 +2438,10 @@ export const useEmailStore = create<EmailStore>((set, get) => ({
   emptyMailbox: async (client, mailboxId) => {
     try {
       set({ isLoading: true, error: null });
-      await resolveActionClient(client).emptyMailbox(mailboxId);
+      const mailbox = resolveActionMailboxes().find(mb => mb.id === mailboxId);
+      const accountId = mailbox?.isShared ? mailbox.accountId : undefined;
+      const jmapMailboxId = mailbox?.originalId || mailboxId;
+      await resolveActionClient(client).emptyMailbox(jmapMailboxId, accountId);
 
       // Clear emails from local state if we're viewing this mailbox
       const currentMailbox = get().selectedMailbox;