A participant never got their email

Internal self-registration sends nothing at all: no confirmation, no wallet pass. It is not a failure and there is nothing to retry. Their ticket and QR code are in the app, under My events, and that is where to point them.

If they want it by email, the organiser can invite them — inviting somebody who is already registered sends the registration email properly.

Registering for a single section sends nothing, for either audience. Only a registration against the event as a whole produces a pass and its email.

The registration email is sent as part of issuing the wallet pass, so an event with the pass turned off sends no registration email either — for everybody on it, not just one person.

The tell is the number affected. One person is causes 1 or 2; a whole event’s worth of people is this one. It is set on the event, by whoever runs it.

Reminders are re-checked when they fall due and skipped if the event is not published at that moment, if the reminder has been deleted, if the event was rescheduled after the reminder was set, or if the event has already started. None of these sends late afterwards.

A paused event that was un-paused the next morning has already missed the reminder that fell due overnight.

Only worth investigating once the four above are ruled out — which is the point of ruling them out first, because four of five reports never reach this stage.

Have the organiser resend it with Send invitation, and check the address on the participant’s record: an external registrant typed their own address into a form, and a typo there looks exactly like a delivery failure.