How Does Bounce Classification Work?
Understanding how Superkabe classifies bounces and enforces thresholds to protect your sender reputation
Quick Answer
Superkabe classifies every bounce event as either a hard bounce (permanent failure) or soft bounce (temporary issue). Only hard bounces count toward your bounce rate. When a mailbox exceeds the 3% hard bounce threshold after a minimum of 60 sends, Superkabe automatically pauses it to prevent reputation damage.
What Is the Difference Between Hard and Soft Bounces?
Hard Bounces
Permanent delivery failures. The email can never be delivered to this address. These are the bounces that damage your reputation.
- • 5xx SMTP codes — Recipient address doesn't exist
- • Invalid domain — The domain has no MX records
- • Mailbox disabled — Account has been deactivated
- • Rejected by policy — Permanent block by receiving server
These count toward your bounce rate and trigger automatic protections.
Soft Bounces
Temporary delivery failures. The email might be deliverable if retried later. These do not count toward your bounce rate.
- • Mailbox full — Recipient's inbox is over quota
- • Server temporarily unavailable — Transient connectivity issue
- • Rate limiting — Sending too fast to this server
- • Message too large — Attachment size exceeded
Logged but do not trigger automatic protections. Your sending platform may retry these.
How Is Bounce Rate Calculated?
Bounce Rate = (Hard Bounces ÷ Total Emails Sent) × 100
Only hard bounces are included. Soft bounces are excluded from this calculation.
What Happens When the Bounce Threshold Is Exceeded?
- 1
Immediate Mailbox Pause
The mailbox is automatically paused and removed from all active campaigns to stop further damage.
- 2
Notification Sent
You receive a critical notification explaining why the mailbox was paused, with the current bounce rate and send count.
- 3
Cooldown Period Begins
A cooldown timer starts (4-48 hours depending on history). This gives receiving servers time to “forget” the bad behavior.
- 4
Auto-Healing Pipeline Starts
The 5-phase recovery process begins automatically. The mailbox progresses through quarantine, restricted sending, warm recovery, and back to healthy.
Where Can I See Bounce Data?
Mailboxes Page
View per-mailbox bounce count, bounce rate (color-coded), delivery failures, recovery phase, clean sends, relapse count, and resilience score. Sort mailboxes by bounce rate to identify problem accounts quickly.
Domains Page
See aggregate bounce rates across all mailboxes on a domain. If 50%+ of a domain's mailboxes are unhealthy, the domain itself is flagged.
Analytics Page
Track daily bounce trends per campaign over time. Bounce spikes are immediately visible in the trend chart as red area fills.
Audit Logs
Every bounce event is recorded with the exact SMTP code, mailbox affected, and resulting system action (pause, phase transition, etc.).
What Is the Resilience Score?
Each mailbox has a Resilience Score (0-100) that reflects its long-term health stability. Frequent relapses lower the score while sustained clean sending raises it.