What’s a “quarantine” or “limbo” folder classification?

Quarantine is a holding state where messages are neither fully delivered nor rejected. Common in corporate and enterprise email environments.

When security gateways or filters are uncertain about a message, they may quarantine it for administrator review. The recipient does not see it until released.

For B2B senders, quarantine can silently absorb messages without generating bounces. You think it delivered, but it is sitting in corporate security limbo.

Your ship arrived at port but is anchored offshore awaiting inspection. Neither admitted nor turned away, just waiting.