Mail that fails a security check on arrival is held in Quarantine instead of being delivered. It stays out of your mail views, search, and notifications, and the sender is never told. After 30 days it's permanently deleted.
Why an email is held
The Quarantine list labels each email with the check it failed:
- Virus means a virus was detected.
- Spam means the email was flagged as potential spam.
- Unverified sender means the email failed DMARC, and the sender's own published policy asks receivers to hold or reject it.
Reading held mail
Open Quarantine in the sidebar. You can read any held email, but remote images don't load, links don't open, attachments can't be downloaded, and there's no reply or forward. A banner shows the date the email will be deleted, and Details shows the result of each check, including virus, spam, SPF, DKIM, and DMARC.
Releasing an email
Release delivers the email as if it had just arrived: your inbox rules run, it gets a category, and it shows up in search.
Releasing doesn't allowlist the sender. The next email from them that fails the same check is held too.
Delete forever
Delete forever removes a held email immediately instead of waiting out the 30 days. It's irreversible.