Deliverability
Deliverability isn’t a feature. It’s the foundation.
App-level circuit breakers for cold email: unsubscribe compliance, bounce auto-pause, inbox cluster protection and follow-up governance.
01 · Compliance
One-click unsubscribe on every send
- List-Unsubscribe and List-Unsubscribe-Post headers (RFC 8058) on every email
- The HTTPS one-click endpoint adds the address to a global do-not-contact list
- Unsubscribe wording in replies is caught by inbox sync as a backup path
List-Unsubscribe: <https://…/unsubscribe?t=…>
List-Unsubscribe-Post: List-Unsubscribe=One-Click
List-Unsubscribe-Post: List-Unsubscribe=One-Click
jan@webspring.ioclicked unsubscribeSuppressed
02 · Bounce guard
The queue pauses before a bad list hurts you
- Pauses sending when the Step 1 bounce rate passes your threshold (5% by default)
- Measured overall and for each campaign, once at least 40 leads have been sent
- Resume starts a fresh window, and a real bounce is never re-marked as valid
Agency outreach · Q40.9%
SaaS founders · EU2.4%
Imported list · Oct6.1%
Queue paused: “Imported list · Oct” is above 5%.
03 · Cluster protection
When one inbox burns, the pool is protected
- Health per inbox: Healthy, Recovery or Blocked
- A blocked inbox cools down for 24 hours and pauses its own follow-ups
- Two blocked inboxes within 24 hours pause the whole queue for review
alex@yourco.comHealthy
sam@yourco.comRecovery · 18h
outreach@yourco.ioHealthy
Follow-ups paused on sam@yourco.com. Step 1 continues on the others.
04 · Follow-up governance
First impressions get priority
- Step 1 goes first whenever follow-ups are due at the same time
- The daily cap is split 70 / 30 between first touches and follow-ups by default
- Follow-ups always leave from the inbox that sent Step 1
210Step 1 cap / day
90Follow-up cap / day
Sticky inbox: each lead’s follow-ups stay with its Step 1 sender
Spec sheet
Safe defaults, tunable in Connect.
Every new workspace starts with conservative limits. Raise them as your inboxes earn reputation.
- Gap between sends
- 1–4 min, randomized
- Hourly cap
- 25 sends
- Daily cap
- 300 sends, split 70 / 30
- Warmup (per inbox, opt-in)
- 15 → 30 → full daily cap
- Bounce guard
- Pause above 5% (40-lead minimum)
- Blocked inbox
- 24 h cooldown, follow-ups paused
- Cluster protection
- 2 blocks in 24 h pause the queue
- Unsubscribe
- On, one-click (RFC 8058)
Honest limits
What we don’t promise.
- Dedicated IPs per inbox. That needs an email service provider or your own mail setup with SPF, DKIM and DMARC on your domain.
- Zero risk on consumer mailboxes. Software lowers the risk; it cannot remove a provider’s terms-of-service exposure.
- Full volume on day one. New inboxes need warmup and low caps before they can carry real volume.
- Rescue for a bad list. Guardrails pause sending; they don’t clean your data. Verify lists before you import them.
We’re upfront about limits so you can scale responsibly, and move to a dedicated sending provider when you’re ready.
Connect an inbox. The guardrails are already on.
Add your inboxes, keep one-click unsubscribe on, and let bounce guard and cluster protection watch your reputation from day one.