cold list · risk · router
Score your list
before it burns
your domain.
Sluice routes every address into the move a cold-outreach operator should actually make — send, suppress, review, or recheck — instead of a vague valid/invalid guess you have to threshold yourself. Catch-all quarantine detection rides on the deep tier.
paste up to 200 addresses · no signup · nothing stored
Five actions. One per address.
No rolling confidence score you then have to threshold. Every row comes back tagged with the campaign move to make on it.
Mailbox verified. Safe in the next campaign.
Catch-all domain — “valid” is unproven. Warm up first.
Role or disposable address. Usually low-value.
No definitive answer — credit refunded. Retry later.
Undeliverable. Sending bounces and burns your domain.
Catch-all → quarantine and the SMTP mailbox probe run on the deep tier. The free report and the standard plan route the other four.
The engine underneath.
Each address falls through four gates. A credit is only spent on rows we could actually answer — the rest are returned to your balance.
- 01
Syntax
Local part, domain shape, length. Catches paste-os instantly.
no I/O - 02
DNS · MX
DoH at 1.1.1.1 with a 60-second cache. Domains without mail land here.
~10ms - 03
Flags
Disposable mailboxes, role accounts, catch-all suspicions — marked risky.
local - 04
SMTP probe
Optional handshake against the resolved MX. Off by default; vendor-pluggable.
opt-in
No data leaves your CSV.
Sluice doesn't store addresses in our database. The original upload sits in your private R2 bucket, the cascade runs in our Workers, and the output CSV lands back in R2 with a signed-link download. Audit log shows you when, who, and which gate every row passed.