diff --git a/internal/customer/repository.go b/internal/customer/repository.go
index afea8d7..1dd3dd8 100644
--- a/internal/customer/repository.go
+++ b/internal/customer/repository.go
@@ -178,7 +178,16 @@ func (r *customerRepository) GetByUsername(ctx context.Context, username string)
 
 // GetByIDs retrieves customers by IDs
 func (r *customerRepository) GetByIDs(ctx context.Context, ids []string) ([]Customer, error) {
-	customers, err := r.ormRepo.FindAll(ctx, bson.M{"_id": bson.M{"$in": ids}}, orm.NewPaginationBuilder().Limit(len(ids)).Build())
+	objectIDs := make([]bson.ObjectID, 0)
+	for _, id := range ids {
+		objectID, err := bson.ObjectIDFromHex(id)
+		if err != nil {
+			return nil, err
+		}
+		objectIDs = append(objectIDs, objectID)
+	}
+
+	customers, err := r.ormRepo.FindAll(ctx, bson.M{"_id": bson.M{"$in": objectIDs}}, orm.NewPaginationBuilder().Limit(len(ids)).Build())
 	if err != nil {
 		if errors.Is(err, orm.ErrDocumentNotFound) {
 			return nil, errors.New("customers not found")
@@ -211,7 +220,16 @@ func (r *customerRepository) GetByRole(ctx context.Context, role CustomerRole) (
 // GetByCompanies retrieves customers by companies
 
 func (r *customerRepository) GetByCompanies(ctx context.Context, companies []string) ([]Customer, error) {
-	customers, err := r.ormRepo.FindAll(ctx, bson.M{"companies": bson.M{"$in": companies}}, orm.NewPaginationBuilder().Build())
+	companyIDs := make([]bson.ObjectID, 0)
+	for _, company := range companies {
+		id, err := bson.ObjectIDFromHex(company)
+		if err != nil {
+			return nil, err
+		}
+		companyIDs = append(companyIDs, id)
+	}
+
+	customers, err := r.ormRepo.FindAll(ctx, bson.M{"companies": bson.M{"$in": companyIDs}}, orm.NewPaginationBuilder().Build())
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/customer/service.go b/internal/customer/service.go
index 78b53d9..7c68b7a 100644
--- a/internal/customer/service.go
+++ b/internal/customer/service.go
@@ -152,7 +152,7 @@ func (s *customerService) Register(ctx context.Context, form *CreateCustomerForm
 		"company_ids": Companies,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: customer.Email,
 		Title:     "Welcome to Opplens",
 		Message:   fmt.Sprintf("Welcome to Opplens\nUsername: %s\nPassword: %s", strings.ToLower(customer.Username), form.Password),
@@ -322,6 +322,7 @@ func (s *customerService) Update(ctx context.Context, id string, form *UpdateCus
 		return nil, errors.New("invalid username format")
 	}
 
+	changeUsername := false
 	// Check if username already exists (if changing username)
 	if form.Username != "" && strings.ToLower(form.Username) != customer.Username {
 		existingCustomer, _ := s.repository.GetByUsername(ctx, strings.ToLower(form.Username))
@@ -329,6 +330,7 @@ func (s *customerService) Update(ctx context.Context, id string, form *UpdateCus
 			return nil, errors.New("customer with this username already exists")
 		}
 		customer.Username = strings.ToLower(form.Username)
+		changeUsername = true
 	}
 
 	// Handle company assignments
@@ -366,6 +368,16 @@ func (s *customerService) Update(ctx context.Context, id string, form *UpdateCus
 		return nil, errors.New("failed to update customer")
 	}
 
+	if changeUsername {
+		go s.notification.SendEmail(context.Background(), notification.Model{
+			Recipient: customer.Email,
+			Title:     "Username Updated",
+			Message:   fmt.Sprintf("Your username has been updated to %s", customer.Username),
+			Type:      "info",
+			Priority:  "important",
+			UserID:    customer.ID.Hex(),
+		})
+	}
 	s.logger.Info("Customer updated successfully", map[string]interface{}{
 		"customer_id": customer.ID,
 		"email":       customer.Email,
@@ -428,7 +440,7 @@ func (s *customerService) UpdateStatus(ctx context.Context, id string, form *Upd
 		"status":      form.Status,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: customer.Email,
 		Title:     "Account Status Updated",
 		Message:   fmt.Sprintf("Your account has been %s", strings.ToUpper(form.Status)),
@@ -779,18 +791,37 @@ func (s *customerService) GetProfileWithCompanies(ctx context.Context, customerI
 // Logout handles customer logout
 func (s *customerService) Logout(ctx context.Context, customerID string, accessToken string) error {
 	s.logger.Info("Customer logout", map[string]interface{}{
-		"customer_id":  customerID,
-		"access_token": accessToken[:10] + "...", // Log only first 10 chars for security
+		"customer_id": customerID,
 	})
 
+	// get customer by id
+	customer, err := s.repository.GetByID(ctx, customerID)
+	if err != nil {
+		s.logger.Error("Failed to get customer for logout", map[string]interface{}{
+			"error":       err.Error(),
+			"customer_id": customerID,
+		})
+	}
+
 	// Invalidate the access token
-	err := s.authService.InvalidateToken(accessToken)
+	err = s.authService.InvalidateToken(accessToken)
 	if err != nil {
 		s.logger.Error("Failed to invalidate access token", map[string]interface{}{
 			"error":       err.Error(),
 			"customer_id": customerID,
 		})
 		// Don't return error here as the customer should still be logged out
+		return errors.New("failed to invalidate access token")
+	}
+
+	// delete device token from customer
+	customer.DeviceToken = make([]string, 0)
+	err = s.repository.Update(ctx, customer)
+	if err != nil {
+		s.logger.Error("Failed to update customer device token", map[string]interface{}{
+			"error":       err.Error(),
+			"customer_id": customerID,
+		})
 	}
 
 	s.logger.Info("Customer logout successful", map[string]interface{}{
@@ -869,7 +900,7 @@ func (s *customerService) RequestResetPassword(ctx context.Context, form *Reques
 	}
 
 	// Send OTP via email
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: form.Email,
 		Title:     "Password Reset",
 		Message:   fmt.Sprintf("Your password reset code is: %s", otpCode),
@@ -1064,7 +1095,7 @@ func (s *customerService) ResetPassword(ctx context.Context, form *ResetPassword
 		"customer_id": customer.ID,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: tokenData.Email,
 		Title:     "Password Reset Success",
 		Message:   "Your password has been reset successfully",
diff --git a/internal/notification/handler.go b/internal/notification/handler.go
index ba173a2..ede2ad4 100644
--- a/internal/notification/handler.go
+++ b/internal/notification/handler.go
@@ -1,6 +1,8 @@
 package notification
 
 import (
+	"context"
+
 	"github.com/asaskevich/govalidator"
 	"github.com/labstack/echo/v4"
 
@@ -48,7 +50,7 @@ func (h *NotificationHandler) Send(c echo.Context) error {
 	}
 
 	// Send notification
-	h.service.Send(c.Request().Context(), &req)
+	go h.service.Send(context.Background(), &req)
 
 	return response.Created(c, nil, "Notification sent successfully")
 }
diff --git a/internal/notification/service.go b/internal/notification/service.go
index 9cad95f..b45f8c1 100644
--- a/internal/notification/service.go
+++ b/internal/notification/service.go
@@ -397,6 +397,10 @@ func (s *notificationService) getCustomers(ctx context.Context, values []string,
 	recipients := make([]notificationRecipient, 0)
 
 	if target == string(TargetAudienceSpecificRole) {
+		if len(values) == 0 {
+			return nil, errors.New("no role provided")
+		}
+
 		customers, err := s.customerService.GetCustomersByRole(ctx, values[0])
 		if err != nil {
 			return nil, err
diff --git a/internal/user/repository.go b/internal/user/repository.go
index 0aa960e..88417db 100644
--- a/internal/user/repository.go
+++ b/internal/user/repository.go
@@ -218,7 +218,16 @@ func (r *userRepository) Delete(ctx context.Context, id string) error {
 
 // GetByIDs retrieves users by IDs
 func (r *userRepository) GetByIDs(ctx context.Context, userIDs []string) ([]User, error) {
-	users, err := r.ormRepo.FindAll(ctx, bson.M{"_id": bson.M{"$in": userIDs}}, orm.NewPaginationBuilder().Limit(len(userIDs)).Build())
+	objectIDs := make([]bson.ObjectID, 0)
+	for _, id := range userIDs {
+		objectID, err := bson.ObjectIDFromHex(id)
+		if err != nil {
+			return nil, err
+		}
+		objectIDs = append(objectIDs, objectID)
+	}
+
+	users, err := r.ormRepo.FindAll(ctx, bson.M{"_id": bson.M{"$in": objectIDs}}, orm.NewPaginationBuilder().Limit(len(userIDs)).Build())
 	if err != nil {
 		return nil, err
 	}
diff --git a/internal/user/service.go b/internal/user/service.go
index d1b6a82..20d6e20 100644
--- a/internal/user/service.go
+++ b/internal/user/service.go
@@ -118,7 +118,7 @@ func (s *userService) Register(ctx context.Context, form *CreateUserForm) (*User
 		"role":     user.Role,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: form.Email,
 		Title:     "Welcome to Opplens",
 		Message:   fmt.Sprintf("Welcome to Opplens\nUsername: %s\nPassword: %s", strings.ToLower(form.Username), form.Password),
@@ -229,7 +229,7 @@ func (s *userService) UpdateStatus(ctx context.Context, id string, form *UpdateU
 		"status":  form.Status,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: user.Email,
 		Title:     "Account Status Updated",
 		Message:   fmt.Sprintf("Your account has been %s", strings.ToUpper(form.Status)),
@@ -495,7 +495,7 @@ func (s *userService) ChangePassword(ctx context.Context, userID string, form *C
 		"user_id": userID,
 	})
 
-	s.notification.SendEmail(ctx, notification.Model{
+	go s.notification.SendEmail(context.Background(), notification.Model{
 		Recipient: user.Email,
 		Title:     "Password Reset Success",
 		Message:   "Your password has been reset successfully",
@@ -632,14 +632,33 @@ func (s *userService) UpdateRole(ctx context.Context, id string, form *UpdateUse
 
 // Logout logs out a user and invalidates tokens
 func (s *userService) Logout(ctx context.Context, userID string, accessToken string) error {
+	// get user by id
+	user, err := s.repository.GetByID(ctx, userID)
+	if err != nil {
+		s.logger.Error("Failed to get user for logout", map[string]interface{}{
+			"error":   err.Error(),
+			"user_id": userID,
+		})
+	}
+
 	// Invalidate the access token
-	err := s.authService.InvalidateToken(accessToken)
+	err = s.authService.InvalidateToken(accessToken)
 	if err != nil {
 		s.logger.Error("Failed to invalidate access token", map[string]interface{}{
 			"error":   err.Error(),
 			"user_id": userID,
 		})
-		// Don't return error here as the user should still be logged out
+		return errors.New("failed to invalidate access token")
+	}
+
+	// delete device token from user
+	user.DeviceToken = make([]string, 0)
+	err = s.repository.Update(ctx, user)
+	if err != nil {
+		s.logger.Error("Failed to update user device token", map[string]interface{}{
+			"error":   err.Error(),
+			"user_id": userID,
+		})
 	}
 
 	s.logger.Info("User logged out successfully", map[string]interface{}{