How Does Mailbox Rotation Work?
Automatic standby swaps that keep your campaigns sending when mailboxes go down
Quick Answer
When a mailbox is paused due to health issues, Superkabe automatically swaps in a healthy standby mailbox from the same domain to keep your campaigns sending. If no standby is available, campaigns continue with their remaining healthy mailboxes. If all mailboxes on a campaign are paused, the campaign itself auto-pauses.
How Rotation Works Step by Step
- 1
Mailbox Is Paused
A mailbox exceeds the bounce threshold (3% after 60+ sends) and is automatically paused. It is removed from all active campaigns on your sending platform.
- 2
Standby Search
Superkabe looks for standby mailboxes on the same domain as the paused mailbox. This preserves domain reputation continuity and DKIM alignment.
- 3
Health & Capacity Check
The standby must be healthy (not paused, not in recovery) and not already assigned to too many campaigns. Overloaded standbys are skipped.
- 4
Platform Swap
The standby mailbox is added to the affected campaigns on your sending platform (Smartlead, Instantly, or EmailBison). This happens via API — no manual action needed.
- 5
Campaign Continues
The campaign keeps sending with the new mailbox. An audit log entry is created recording the swap.
What Makes a Valid Standby?
Eligible for Rotation
- ✓Status is healthy
- ✓On the same domain as the paused mailbox
- ✓Not already in too many campaigns
- ✓Connected to the sending platform
Not Eligible
- ✗Currently paused or in any recovery phase
- ✗On a different domain
- ✗Already at maximum campaign capacity
- ✗Not connected to the sending platform
What If No Standby Is Available?
Some Mailboxes Still Healthy
The campaign continues sending with its remaining healthy mailboxes. Volume will naturally decrease since fewer mailboxes are active. Superkabe logs a warning so you know the campaign is running below capacity.
All Mailboxes Paused
If every single mailbox assigned to a campaign is paused (or removed during recovery), the campaign itself is automatically paused on the sending platform. This is the only condition that triggers a campaign-level pause — bounce rate alone never pauses a campaign directly.
Example Scenario
You have 3 mailboxes on acmecorp.com:
• john@acmecorp.com — Active in Campaign A and Campaign B
• sarah@acmecorp.com — Active in Campaign A
• mike@acmecorp.com — Standby (healthy, not in any campaigns)
What happens when john@acmecorp.com bounces above 3%:
1. john@acmecorp.com is paused and removed from Campaign A and Campaign B
2. Superkabe finds mike@acmecorp.com as an eligible standby (same domain, healthy, low campaign count)
3. mike@acmecorp.com is added to Campaign A and Campaign B via the sending platform API
4. Both campaigns continue sending without interruption
5. john@acmecorp.com enters the healing pipeline and will recover over the coming days
Best Practice: Keep Standby Mailboxes Ready
For every 2–3 active mailboxes on a domain, maintain at least 1 warmed-up standby. This ensures rotation can happen instantly when needed. A standby mailbox should be:
- • Fully warmed up and healthy
- • Connected to your sending platform
- • On the same domain as your active mailboxes
- • Not assigned to any campaigns (reserved for rotation)
Important Note on Platform Sync
Mailbox rotation happens on your sending platform (Smartlead, Instantly, EmailBison) via their API. If the platform API is temporarily unavailable, the swap will be retried. Check your audit logs if a rotation seems delayed — you’ll see the exact API response and retry attempts.