Two system emails are triggered automatically (edit their content under Marketing > System emails):

• user_affiliates_affiliateuser_create — sent to the affiliate's email every time their affiliate record is saved (including the first creation), so they know they have been enrolled.
• user_affiliates_payout_create — sent to the affiliate when you create a payout, with the payout details.

Commission status changes (paid/unpaid/rejected without a payout) do not send emails.