How does a line manager receive notification emails?

To Receive Email Notifications 

1. Setup an approval record with 1 stage that goes to the line manager for approval.
   Go to Setup> Approvals.
2. Create a user account with a real email address for the line manager.
   Go to Setup> People
3. Create an account for another user and add the Line Manager and Approval Workflow.
   Go to Setup> People
4. Invite the user to sign in to Capture Expense.
   Go to User record> Actions> Display Invite Link
5. As a user, raise an expense claim.
   Go to Expense
6. As a user, submit the expense claim for approval.
   Go to Expenses> Draft.
   The line manager will receive a notification to approve the Expense claim.