How quarantine works
Quarantine is a holding area for emails that look suspicious but aren't certain spam. Instead of delivering them to your inbox or deleting them outright, Cleanbox holds them for your review. This way, you never miss a legitimate email that happened to trigger a spam filter.
Why emails end up in quarantine
A message is quarantined when its spam score exceeds the threshold set for the alias it was sent to, but doesn't hit the absolute rejection limit. There are several reasons this can happen:
- High spam score — The message triggered multiple spam detection rules (suspicious links, known spam patterns, misleading headers) and the combined score exceeded your threshold.
- Failed authentication — The sender's domain failed SPF, DKIM, or DMARC validation, which adds points to the spam score.
- Suspicious content — The email body contains patterns commonly associated with phishing or scam messages.
- New or unknown sender — First-time senders with no reputation may score higher than established contacts.
Whitelisted contacts bypass quarantine entirely. If a sender you trust keeps ending up in quarantine, add them to your whitelist via the contact rules.
Reviewing quarantined messages
You can access quarantine from your dashboard. The quarantine view shows all held messages across all your aliases, with the most recent messages first. For each message you can see:
- Sender address and name
- Subject line
- Which alias received the message
- When it arrived
- The spam score and reason for quarantine
Click on any message to see a preview of its content, the full spam report, and available actions.
Actions you can take
Deliver to inbox
If the message is legitimate, click Deliver to release it from quarantine and forward it to your mailbox. The message status changes from "quarantined" to "delivered" and it appears in your inbox as normal.
Delete permanently
If the message is spam, click Delete to permanently remove it. Deleted quarantine messages cannot be recovered.
Train the spam filter
When you deliver a quarantined message, you can optionally mark it as "not spam". This feeds back into the spam detection system and helps improve accuracy for future messages from that sender. Similarly, if a message was borderline, you can mark it as "spam" to reinforce the detection.
Reducing false positives
If too many legitimate emails are ending up in quarantine, you have several options to fine-tune your setup:
Adjust your spam threshold
Each alias has its own spam threshold. A lower threshold is more aggressive (catches more spam but may flag legitimate emails). A higher threshold is more lenient. You can adjust this per alias in the alias settings.
- Recommended for public aliases (used on websites, forms): threshold of 3–5
- Recommended for personal aliases (used with trusted services): threshold of 7–10
Whitelist trusted senders
Set a contact rule to whitelist for any sender you trust. Whitelisted senders skip spam evaluation entirely and are always delivered.
Create filter rules
If emails from a specific domain or with specific subject patterns keep getting quarantined, create an allow filter rule for them. Filter rules are evaluated before quarantine decisions.
Quarantine retention
Quarantined messages follow the same retention policy as all other messages in your account. Depending on your plan, messages are retained for 7 to 365 days. After the retention period, quarantined messages that were never reviewed are automatically deleted.
We recommend checking your quarantine regularly — at least once a week — to catch any false positives early. The dashboard shows a quarantine count badge so you can see at a glance if there are messages waiting for your review.
