Outbound Queue¶
The Outbound Queue shows messages from your organization that are waiting to be delivered, in the process of being retried, or have been manually held. Use it to investigate delivery problems or take action on specific messages.
Accessing the Queue¶
Go to Outbound Queue in the left sidebar.
Queue Status Values¶
| Status | Meaning |
|---|---|
| queued | Waiting for its first delivery attempt. Messages normally leave this state within seconds. |
| deferred | A delivery attempt failed with a temporary error (e.g. remote server unavailable). The server will retry automatically on an increasing schedule. |
| held | Manually paused by an administrator. Will not be sent until released. |
| frozen | Failed permanently after exhausting all retries. Will not be retried unless manually released. |
Filtering¶
Use the Status dropdown to show only messages in a specific state. Click ↻ Refresh to reload the list.
The queue refreshes automatically every 30 seconds.
Queue Columns¶
| Column | Description |
|---|---|
| Queued At | When the message entered the queue |
| From | The sender address |
| To | The recipient address(es) |
| Subject | The message subject |
| Status | Current queue status |
| Attempts | How many delivery attempts have been made |
| Next Retry | How long until the next automatic retry (for deferred messages) |
Click any row to see the full Queue Entry detail panel, including message size, last error from the remote server, and the delivery trail.
Actions¶
Each row has one or more action buttons depending on the message's status:
| Action | Available when | What it does |
|---|---|---|
| Retry | Deferred, held, frozen | Forces an immediate delivery attempt instead of waiting for the next scheduled retry |
| Hold | Queued, deferred | Pauses the message; it will not be sent until you release it |
| Release | Held, frozen | Resumes delivery; schedules an immediate retry |
| Cancel | Any status | Permanently discards the message |
Canceling a Message¶
When you click Cancel, a confirmation dialog appears with a checkbox: Send bounce notification to sender.
- Checked (default for older messages): A bounce email is sent to the original sender informing them the message could not be delivered.
- Unchecked: The message is silently discarded with no notification.
Click Discard to confirm. Cancellation is permanent.
Delivery Trail¶
The detail panel for each queue entry shows a Delivery Trail — a timestamped log of every delivery attempt, including the error response from the remote mail server. This is useful for diagnosing why a message is bouncing or deferring.
Common temporary errors:
- Remote server connection refused or timeout (network issue on remote end)
- 421 or 450-series SMTP codes (remote server busy or rate-limiting)
Common permanent errors:
- 5xx-series SMTP codes, typically meaning the recipient address doesn't exist or the remote server is rejecting mail from your domain
- SPF/DKIM failures suggesting a DNS configuration problem