- Quarantine is a secure storage area in Exchange Online where extremely suspicious or dangerous emails are kept.
- These emails may contain viruses, malware, or links that have been identified with a very high level of trust as suspicious.
- For these two types of malicious emails (viruses/malware and phishing links), the system will always place them in quarantine without exception.
- Microsoft Exchange Online Protection uses advanced identification techniques to analyze every incoming email.
- Filtering : If an email is identified as highly suspicious, it will be placed in quarantine and will not be delivered to your inbox.
- Notification : As a user, you will receive a weekly summary of your quarantined emails.
- Protection : To prevent malicious actors from directly reaching end users with potentially dangerous emails.
- Review : Users can review quarantined emails in a secure environment (preview via a web browser), where they can choose to permanently delete an email or request its release.
- Release : This action is not immediate, as the email will require review by an administrator before being deemed safe for release.
From the Microsoft 365 quarantine web portal at this link.