The unsuitable user list on the system admin page is designed to allow both monitoring of when the 'unsuitable' flag is used (View application) and removal of the flag should it have been applied in error (Delete).
When marking an applicant as 'unsuitable' as opposed to 'not selected', the hiring manager is noting that the applicant should not be hired for any role within the organisation.
Assemble maintains a hashed email list of all 'unsuitable' applicants independent of the application process. If applied in error, setting the rejection reason to 'not selected' will not remove the entry from the unsuitable user list. This will need to be completed by a system admin as a separate step.
While the hash cannot be reversed to show the original email address, future application emails can be hashed and compared to the stored hash. Should a hash match, the system will know this was previously marked unsuitable and a flag will be shown on the application to make the manager aware.
Once anonymised (default one month for closed applications) the applicant's name will not show. For historical applications you will need to rely on the date and role originally applied for to remove an entry because the email cannot be recovered.