diff --git a/backend/app/routers/imap.py b/backend/app/routers/imap.py
index 2199f03..1592b7c 100644
--- a/backend/app/routers/imap.py
+++ b/backend/app/routers/imap.py
@@ -8,6 +8,7 @@ from app.core.imap import _test_imap_connection, get_folders
 from app.core.logging import get_logger
 from app.crud.settings import create_or_update_settings, get_settings
 from app.schemas.settings import Settings, SettingsCreate
+from app.services.email_processor import process_emails
 
 logger = get_logger(__name__)
 router = APIRouter()
@@ -71,3 +72,15 @@ def read_folders(db: Session = Depends(get_db)):
 
     logger.info(f"Found {len(folders)} IMAP folders")
     return folders
+
+
+@router.post("/imap/process")
+def trigger_email_processing(db: Session = Depends(get_db)):
+    """Trigger the email processing manually."""
+    logger.info("Request to manually trigger email processing")
+    try:
+        process_emails(db)
+        return {"message": "Email processing triggered successfully."}
+    except Exception as e:
+        logger.error(f"Error triggering email processing: {e}", exc_info=True)
+        raise HTTPException(status_code=500, detail=str(e))
diff --git a/backend/app/tests/test_routers.py b/backend/app/tests/test_routers.py
index 59054e0..ea9016a 100644
--- a/backend/app/tests/test_routers.py
+++ b/backend/app/tests/test_routers.py
@@ -102,6 +102,15 @@ def test_get_imap_folders(mock_imap, client: TestClient):
     assert response.json() == ["INBOX", "Processed"]
 
 
+@patch("app.routers.imap.process_emails")
+def test_trigger_email_processing(mock_process_emails, client: TestClient):
+    """Test triggering email processing manually."""
+    response = client.post("/imap/process")
+    assert response.status_code == 200
+    assert response.json() == {"message": "Email processing triggered successfully."}
+    mock_process_emails.assert_called_once()
+
+
 def test_create_newsletter(client: TestClient):
     """Test creating a newsletter."""
     unique_email = f"newsletter_{uuid.uuid4()}@example.com"
diff --git a/frontend/components/letterfeed/Header.tsx b/frontend/components/letterfeed/Header.tsx
index 3e2b9bd..e868714 100644
--- a/frontend/components/letterfeed/Header.tsx
+++ b/frontend/components/letterfeed/Header.tsx
@@ -1,6 +1,10 @@
+"use client"
+
 import { Button } from "@/components/ui/button"
-import { Plus, Settings } from "lucide-react"
+import { processEmails } from "@/lib/api"
+import { Mail, Plus, Settings } from "lucide-react"
 import Image from "next/image"
+import { toast } from "sonner"
 
 interface HeaderProps {
   onOpenAddNewsletter: () => void
@@ -8,13 +12,35 @@ interface HeaderProps {
 }
 
 export function Header({ onOpenAddNewsletter, onOpenSettings }: HeaderProps) {
+  const handleProcessEmails = async () => {
+    try {
+      await processEmails()
+      toast.success("Email processing started successfully!")
+    } catch (error) {
+      const message =
+        error instanceof Error
+          ? error.message
+          : "An unexpected error occurred."
+      console.error(error)
+      toast.error(message)
+    }
+  }
+
   return (
     <div className="flex items-center justify-between mb-8">
       <div className="flex items-center gap-4">
-        <Image src="/logo.png" alt="LetterFeed Logo" width={48} height={48} className="rounded-lg" />
+        <Image
+          src="/logo.png"
+          alt="LetterFeed Logo"
+          width={48}
+          height={48}
+          className="rounded-lg"
+        />
         <div>
           <h1 className="text-3xl font-bold text-gray-900">LetterFeed</h1>
-          <p className="text-gray-600 mt-1">Read your newsletters as RSS feeds!</p>
+          <p className="text-gray-600 mt-1">
+            Read your newsletters as RSS feeds!
+          </p>
         </div>
       </div>
 
@@ -24,6 +50,11 @@ export function Header({ onOpenAddNewsletter, onOpenSettings }: HeaderProps) {
           Add Newsletter
         </Button>
 
+        <Button variant="outline" onClick={handleProcessEmails}>
+          <Mail className="w-4 h-4 mr-2" />
+          Process Now
+        </Button>
+
         <Button variant="outline" onClick={onOpenSettings}>
           <Settings className="w-4 h-4 mr-2" />
           Settings
diff --git a/frontend/components/letterfeed/__tests__/Header.test.tsx b/frontend/components/letterfeed/__tests__/Header.test.tsx
index e977feb..0939b37 100644
--- a/frontend/components/letterfeed/__tests__/Header.test.tsx
+++ b/frontend/components/letterfeed/__tests__/Header.test.tsx
@@ -1,30 +1,120 @@
-import React from "react"
-import { render, screen, fireEvent } from "@testing-library/react"
-import "@testing-library/jest-dom"
+import { render, screen, fireEvent, waitFor } from "@testing-library/react"
 import { Header } from "../Header"
+import { Toaster } from "@/components/ui/sonner"
+import { toast } from "sonner"
+import * as api from "@/lib/api"
+
+jest.mock("@/lib/api")
+const mockedApi = api as jest.Mocked<typeof api>
+
+// Mock the toast functions
+jest.mock("sonner", () => {
+  const original = jest.requireActual("sonner")
+  return {
+    ...original,
+    toast: {
+      success: jest.fn(),
+      error: jest.fn(),
+    },
+  }
+})
 
 describe("Header", () => {
-  it("renders the title and description", () => {
-    render(<Header onOpenAddNewsletter={() => {}} onOpenSettings={() => {}} />)
+  const onOpenAddNewsletter = jest.fn()
+  const onOpenSettings = jest.fn()
+  const consoleError = jest.spyOn(console, "error").mockImplementation(() => {})
+
+  beforeEach(() => {
+    jest.clearAllMocks()
+    consoleError.mockClear()
+  })
+
+  afterAll(() => {
+    consoleError.mockRestore()
+  })
+
+  it("renders the header with title and buttons", () => {
+    render(
+      <Header
+        onOpenAddNewsletter={onOpenAddNewsletter}
+        onOpenSettings={onOpenSettings}
+      />
+    )
     expect(screen.getByText("LetterFeed")).toBeInTheDocument()
-    expect(screen.getByText("Read your newsletters as RSS feeds!")).toBeInTheDocument()
+    expect(screen.getByText("Add Newsletter")).toBeInTheDocument()
+    expect(screen.getByText("Settings")).toBeInTheDocument()
+    expect(screen.getByText("Process Now")).toBeInTheDocument()
   })
 
   it('calls onOpenAddNewsletter when "Add Newsletter" button is clicked', () => {
-    const handleOpenAdd = jest.fn()
-    render(<Header onOpenAddNewsletter={handleOpenAdd} onOpenSettings={() => {}} />)
-
-    const addButton = screen.getByRole("button", { name: /Add Newsletter/i })
-    fireEvent.click(addButton)
-    expect(handleOpenAdd).toHaveBeenCalledTimes(1)
+    render(
+      <Header
+        onOpenAddNewsletter={onOpenAddNewsletter}
+        onOpenSettings={onOpenSettings}
+      />
+    )
+    fireEvent.click(screen.getByText("Add Newsletter"))
+    expect(onOpenAddNewsletter).toHaveBeenCalledTimes(1)
   })
 
   it('calls onOpenSettings when "Settings" button is clicked', () => {
-    const handleOpenSettings = jest.fn()
-    render(<Header onOpenAddNewsletter={() => {}} onOpenSettings={handleOpenSettings} />)
+    render(
+      <Header
+        onOpenAddNewsletter={onOpenAddNewsletter}
+        onOpenSettings={onOpenSettings}
+      />
+    )
+    fireEvent.click(screen.getByText("Settings"))
+    expect(onOpenSettings).toHaveBeenCalledTimes(1)
+  })
 
-    const settingsButton = screen.getByRole("button", { name: /Settings/i })
-    fireEvent.click(settingsButton)
-    expect(handleOpenSettings).toHaveBeenCalledTimes(1)
+  it('calls the process emails API when "Process Now" button is clicked and shows success toast', async () => {
+    mockedApi.processEmails.mockResolvedValue({ message: "Success" })
+
+    render(
+      <>
+        <Header
+          onOpenAddNewsletter={onOpenAddNewsletter}
+          onOpenSettings={onOpenSettings}
+        />
+        <Toaster />
+      </>
+    )
+
+    fireEvent.click(screen.getByText("Process Now"))
+
+    await waitFor(() => {
+      expect(api.processEmails).toHaveBeenCalledTimes(1)
+    })
+
+    await waitFor(() => {
+      expect(toast.success).toHaveBeenCalledWith(
+        "Email processing started successfully!"
+      )
+    })
+  })
+
+  it("shows an error toast if the process emails API call fails", async () => {
+    mockedApi.processEmails.mockRejectedValue(new Error("Failed to process"))
+
+    render(
+      <>
+        <Header
+          onOpenAddNewsletter={onOpenAddNewsletter}
+          onOpenSettings={onOpenSettings}
+        />
+        <Toaster />
+      </>
+    )
+
+    fireEvent.click(screen.getByText("Process Now"))
+
+    await waitFor(() => {
+      expect(api.processEmails).toHaveBeenCalledTimes(1)
+    })
+
+    await waitFor(() => {
+      expect(toast.error).toHaveBeenCalledWith("Failed to process")
+    })
   })
 })
diff --git a/frontend/components/ui/sonner.tsx b/frontend/components/ui/sonner.tsx
new file mode 100644
index 0000000..aaa043c
--- /dev/null
+++ b/frontend/components/ui/sonner.tsx
@@ -0,0 +1,27 @@
+"use client"
+
+import { Toaster as Sonner } from "sonner"
+
+type ToasterProps = React.ComponentProps<typeof Sonner>
+
+const Toaster = ({ ...props }: ToasterProps) => {
+  return (
+    <Sonner
+      className="toaster group"
+      toastOptions={{
+        classNames: {
+          toast:
+            "group toast group-[.toaster]:bg-background group-[.toaster]:text-foreground group-[.toaster]:border-border group-[.toaster]:shadow-lg",
+          description: "group-[.toast]:text-muted-foreground",
+          actionButton:
+            "group-[.toast]:bg-primary group-[.toast]:text-primary-foreground",
+          cancelButton:
+            "group-[.toast]:bg-muted group-[.toast]:text-muted-foreground",
+        },
+      }}
+      {...props}
+    />
+  )
+}
+
+export { Toaster }
diff --git a/frontend/jest.setup.js b/frontend/jest.setup.js
index 7b0828b..98acb62 100644
--- a/frontend/jest.setup.js
+++ b/frontend/jest.setup.js
@@ -1 +1,15 @@
 import '@testing-library/jest-dom';
+
+Object.defineProperty(window, 'matchMedia', {
+  writable: true,
+  value: jest.fn().mockImplementation(query => ({
+    matches: false,
+    media: query,
+    onchange: null,
+    addListener: jest.fn(), // deprecated
+    removeListener: jest.fn(), // deprecated
+    addEventListener: jest.fn(),
+    removeEventListener: jest.fn(),
+    dispatchEvent: jest.fn(),
+  })),
+});
diff --git a/frontend/package-lock.json b/frontend/package-lock.json
index 29829e3..ea8c71d 100644
--- a/frontend/package-lock.json
+++ b/frontend/package-lock.json
@@ -19,6 +19,7 @@
         "next": "15.4.1",
         "react": "19.1.0",
         "react-dom": "19.1.0",
+        "sonner": "^2.0.6",
         "tailwind-merge": "^3.3.1"
       },
       "devDependencies": {
@@ -11929,6 +11930,16 @@
         "node": ">=8"
       }
     },
+    "node_modules/sonner": {
+      "version": "2.0.6",
+      "resolved": "https://registry.npmjs.org/sonner/-/sonner-2.0.6.tgz",
+      "integrity": "sha512-yHFhk8T/DK3YxjFQXIrcHT1rGEeTLliVzWbO0xN8GberVun2RiBnxAjXAYpZrqwEVHBG9asI/Li8TAAhN9m59Q==",
+      "license": "MIT",
+      "peerDependencies": {
+        "react": "^18.0.0 || ^19.0.0 || ^19.0.0-rc",
+        "react-dom": "^18.0.0 || ^19.0.0 || ^19.0.0-rc"
+      }
+    },
     "node_modules/source-map": {
       "version": "0.6.1",
       "resolved": "https://registry.npmjs.org/source-map/-/source-map-0.6.1.tgz",
diff --git a/frontend/package.json b/frontend/package.json
index ae9c02f..76dc71f 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -21,6 +21,7 @@
     "next": "15.4.1",
     "react": "19.1.0",
     "react-dom": "19.1.0",
+    "sonner": "^2.0.6",
     "tailwind-merge": "^3.3.1"
   },
   "devDependencies": {
diff --git a/frontend/src/app/layout.tsx b/frontend/src/app/layout.tsx
index a44c127..31ce70d 100644
--- a/frontend/src/app/layout.tsx
+++ b/frontend/src/app/layout.tsx
@@ -1,26 +1,27 @@
-import type { Metadata } from "next";
-import { Geist, Geist_Mono } from "next/font/google";
-import "./globals.css";
+import type { Metadata } from "next"
+import { Geist, Geist_Mono } from "next/font/google"
+import "./globals.css"
+import { Toaster } from "@/components/ui/sonner"
 
 const geistSans = Geist({
   variable: "--font-geist-sans",
   subsets: ["latin"],
-});
+})
 
 const geistMono = Geist_Mono({
   variable: "--font-geist-mono",
   subsets: ["latin"],
-});
+})
 
 export const metadata: Metadata = {
   title: "LetterFeed",
   description: "Read your newsletters as RSS feeds!",
-};
+}
 
 export default function RootLayout({
   children,
 }: Readonly<{
-  children: React.ReactNode;
+  children: React.ReactNode
 }>) {
   return (
     <html lang="en">
@@ -28,7 +29,8 @@ export default function RootLayout({
         className={`${geistSans.variable} ${geistMono.variable} antialiased`}
       >
         {children}
+        <Toaster />
       </body>
     </html>
-  );
+  )
 }
diff --git a/frontend/src/lib/api.ts b/frontend/src/lib/api.ts
index a9c5b64..1db62ad 100644
--- a/frontend/src/lib/api.ts
+++ b/frontend/src/lib/api.ts
@@ -137,6 +137,18 @@ export async function testImapConnection(): Promise<{ message: string }> {
     return response.json();
 }
 
+export async function processEmails(): Promise<{ message: string }> {
+    const response = await fetch(`${API_BASE_URL}/imap/process`, {
+        method: 'POST',
+    });
+    if (!response.ok) {
+        const error = await response.json();
+        throw new Error(error.detail || "Failed to process emails");
+    }
+    return response.json();
+}
+
 export function getFeedUrl(newsletterId: number): string {
     return `${API_BASE_URL}/feeds/${newsletterId}`;
 }
+