The Flow trigger dropdown lists the customer-facing system events. They include:

• Customer account: New Registered User, New Email Verification Code Sent, User: Recovery (forgot password), User: Birthday, User: Giftcard, User: Referrer, User: Referee, User: New Newsletter (newsletter form signup), Affiliate User: Create, Affiliate Payout: Create.
• Orders: Order: Create, Order: Grab & Go Placed, Order: Pickup Ready, Order: Refund, Order: Referral, Order: Referee, Order: Abandoned Cart, User: First Order, Order: Delivery Date, Customer: Complete Your Payment, Bag: Returned.
• Subscriptions: Subscription: Create, Skip a delivery, Cancel, Pause, Change Address, Renew, Renew Error, Meals To Choose Reminder, Request Change Address, Request Cancel, Request Pause, Request Unpause.
• Proposals/Catering: Proposal: Payment Reminder, Proposal: Payment Past Due, Proposal: New, Proposal: New Unread Message, Recurring Proposals: Auto-Charge Error.

A flow only fires when the corresponding system email is active in Marketing > System emails; if that email is switched off, the event is not raised for flows either.