diff --git a/addons/sale/models/sale_order.py b/addons/sale/models/sale_order.py
index 6e147242737..eb489b0034b 100644
--- a/addons/sale/models/sale_order.py
+++ b/addons/sale/models/sale_order.py
@@ -542,11 +542,13 @@ class SaleOrder(models.Model):
         return result
 
     def _compute_field_value(self, field):
+        if field.name == 'invoice_status' and not self.env.context.get('mail_activity_automation_skip'):
+            filtered_self = self.filtered(lambda so: (so.user_id or so.partner_id.user_id) and so._origin.invoice_status != 'upselling')
         super()._compute_field_value(field)
         if field.name != 'invoice_status' or self.env.context.get('mail_activity_automation_skip'):
             return
 
-        upselling_orders = self.filtered(lambda so: (so.user_id or so.partner_id.user_id) and so.invoice_status == 'upselling')
+        upselling_orders = filtered_self.filtered(lambda so: so.invoice_status == 'upselling')
         if not upselling_orders:
             return
 
diff --git a/addons/sale_timesheet/tests/test_sale_timesheet.py b/addons/sale_timesheet/tests/test_sale_timesheet.py
index 925ca719d63..f7d87d58727 100644
--- a/addons/sale_timesheet/tests/test_sale_timesheet.py
+++ b/addons/sale_timesheet/tests/test_sale_timesheet.py
@@ -666,3 +666,70 @@ class TestSaleTimesheet(TestCommonSaleTimesheet):
         self.assertEqual(self.partner_b, task_so1_timesheet2.partner_id, "The Task's second Timesheet entry should have its partner changed, as it was not invoiced and the Task's partner/customer changed.")
         self.assertEqual(so1_product_global_project_so_line, task_so1_timesheet1.so_line, "The Task's first Timesheet entry should not have changed as it was already invoiced (its so_line should still be equal to the first Sales Order line).")
         self.assertEqual(so2_product_global_project_so_line, task_so1_timesheet2.so_line, "The Task's second Timesheet entry should have it's so_line changed, as the Sales Order Item of the Task changed, and this entry was not invoiced.")
+
+    def test_timesheet_upsell(self):
+        """ Test timesheet upselling and email """
+
+        sale_order = self.env['sale.order'].with_context(mail_notrack=True, mail_create_nolog=True).create({
+            'partner_id': self.partner_a.id,
+            'partner_invoice_id': self.partner_a.id,
+            'partner_shipping_id': self.partner_a.id,
+            'user_id': self.user_employee_company_B.id,
+        })
+        # create SO and confirm it
+        uom_days = self.env.ref('uom.product_uom_day')
+        sale_order_line = self.env['sale.order.line'].create({
+            'order_id': sale_order.id,
+            'name': self.product_order_timesheet3.name,
+            'product_id': self.product_order_timesheet3.id,
+            'product_uom_qty': 1,
+            'product_uom': uom_days.id,
+            'price_unit': self.product_order_timesheet3.list_price,
+        })
+        sale_order.action_confirm()
+        task = sale_order_line.task_id
+
+        # let's log some timesheets
+        self.env['account.analytic.line'].create({
+            'name': 'Test Line',
+            'project_id': task.project_id.id,
+            'task_id': task.id,
+            'unit_amount': 8,
+            'employee_id': self.employee_manager.id,
+        })
+
+        sale_order._create_invoices()
+        last_message_id = self.env['mail.message'].search([('model', '=', 'sale.order'), ('res_id', '=', sale_order.id)], limit=1).id or 0
+        self.env['account.analytic.line'].create({
+            'name': 'Test Line',
+            'project_id': task.project_id.id,
+            'task_id': task.id,
+            'unit_amount': 5,
+            'employee_id': self.employee_user.id,
+        })
+
+        self.assertEqual(sale_order.invoice_status, 'upselling', 'Sale Timesheet: "invoice on delivery" timesheets should not modify the invoice_status of the so')
+        message_sent = self.env['mail.message'].search([
+            ('id', '>', last_message_id),
+            ('subject', 'like', 'Upsell'),
+            ('model', '=', 'sale.order'),
+            ('res_id', '=', sale_order.id),
+        ])
+
+        self.assertEqual(len(message_sent), 1, 'Sale Timesheet: An email should always be sent to the saleperson when the state of the sale order change to upselling')
+
+        self.env['account.analytic.line'].create({
+            'name': 'Test Line',
+            'project_id': task.project_id.id,
+            'task_id': task.id,
+            'unit_amount': 5,
+            'employee_id': self.employee_user.id,
+        })
+
+        message_sent = self.env['mail.message'].search([
+            ('id', '>', last_message_id),
+            ('subject', 'like', 'Upsell'),
+            ('model', '=', 'sale.order'),
+            ('res_id', '=', sale_order.id),
+        ])
+        self.assertEqual(len(message_sent), 1, 'Sale Timesheet: An email should only be sent to the saleperson when the state of the sale order change to upselling')