Start codes can be unsubscribed so that the respondent will no longer receive emails from the connected project in the future.
Unsubscribing can be done on this page (with reason: helpdesk) or via the unsubscribe page, where a reason can be selected if multiple options exist. Note: unsubscribing is project-specific, and the respondent may still receive emails from other projects.
It is also possible to resubscribe a start code from this page.