How does SenderSignal detect blacklist listings?

Checks run immediately when you add an asset, on your plan schedule, and whenever you rescan. When a listing is newly detected, alerts can reach your team through the channels you configure.

Which blacklists does SenderSignal monitor?

SenderSignal monitors 44 or more blacklist vendors, including major DNSBL and URIBL feeds. The vendors available to you depend on your subscription plan.

Where do alerts get delivered?

Email, Slack, and HTTPS webhooks. Webhooks work well for PagerDuty, Microsoft Teams adapters, and custom automation. You can subscribe each channel to the event types that matter to your team.

Alerts

Alert channels

Email (multiple recipients), Slack, and custom webhooks: each channel chooses which events to receive.

Channel types

Email

Add one or more recipient addresses per channel
Each address receives HTML + plain-text alert emails
Create separate channels for ops vs marketing if you want different event subscriptions
Use Send test to verify delivery before going live

Multiple emails: add every stakeholder on the same channel, or split into channels (e.g. “Critical: on-call” vs “All listings: team inbox”).

Slack

Connect via incoming webhook URL from your Slack workspace
Choose channel name for display in SenderSignal
Alerts post as formatted messages with asset, severity, and deep link back to SenderSignal
Subscribe to the event types relevant to that Slack room (#deliverability-alerts vs #security)

Webhook (HTTPS)

POST JSON payload to your endpoint when matching events fire
Optional shared secret header for verification
Ideal for PagerDuty, Microsoft Teams adapters, custom ticketing, or internal automation
Retry behavior and delivery logs visible under Alerts → delivery history

Creating a channel

Alerts → Channels → Add channel
Pick type: Email, Slack, or Webhook
Enter configuration (addresses, webhook URL, secret)
Select event types this channel should receive
Save and run Test

Event subscriptions

Each channel maintains its own checklist of events (listed, delisted, score_drop, postmaster reputation change, etc.). Unchecked events never hit that channel: even if a rule would otherwise match.

Webhook payload basics

Webhook POST bodies include structured fields such as:

Alert type and severity
Asset value (domain or IP)
Human-readable title and message
Timestamp and link to the alert in SenderSignal
Metadata rows (vendor name, old/new score, policy details)

Your endpoint should return HTTP 2xx quickly. Timeouts are logged as delivery failures you can retry from the UI.

Global settings vs channels

Alert Settings toggles whether certain event families are generated at all (e.g. Postmaster spam rate alerts). Channels only deliver events that were created and that they subscribe to.

Security tips

Rotate webhook secrets periodically
Use HTTPS endpoints only
Restrict Slack webhooks to dedicated channels, not #general
Remove recipients when people leave the team

Rules & routing →