solve mail backend 3

app/api/mail/login/route.ts

@@ -14,6 +14,18 @@ export async function POST(request: Request) {
       );
     }
 
+    // Verify user exists
+    const user = await prisma.user.findUnique({
+      where: { id: session.user.id }
+    });
+
+    if (!user) {
+      return NextResponse.json(
+        { error: 'User not found' },
+        { status: 404 }
+      );
+    }
+
     const { email, password, host, port } = await request.json();
 
     if (!email || !password || !host || !port) {