If a user account is created with a username and password, but with no email address, that account becomes a global quarantine account and all users will use that same quarantine screen to search for their blocked email. This approach might not be desirable for privacy reasons.

One global user is setup (no email addresses are entered)

NOTE: Anyone can search for their blocked email from the same Quarantine screen, search through all emails in the 'All Email' screen or look at and rescue delayed email in the Grey Listing screen.