Everything to run email,
under one roof.
Routing rules. Failover. Warmup. Suppression sync. One subscriber timeline. AI agent API. Webhooks. Analytics. The control plane your team and your AI agents share.
Send the right way, every time.
Per-route rules. Per-message cost calc. Re-evaluated live, every time you ship.
your sends
Rules engine
Code-free conditions on type, geo, segment, volume, time. Version-controlled, diff-able, revertable. Test in dry-run before flipping live.
Cost-aware routing
Every message routes to the cheapest provider that still meets its rules. We model price-per-message for each ESP on your stack, recomputed hourly.
Live re-evaluation
Change a rule and traffic shifts inside a minute. Reputation drop on one provider? Cost spike? Senderstool re-balances without redeploys.
Sending you can bet payroll on.
Failover in seconds. Warmup, managed. Suppression, synced across every provider you run.
Failover & uptime
Per-route, per-provider health checks every 10 seconds. When SES throttles or Postmark hits an incident, traffic reroutes in < 5 seconds with zero dropped messages.
Warmup management
IP pools graduated automatically. New sending domains hit full throughput on schedule, with bounce-rate guardrails that pause warmup if reputation tanks.
Suppression list sync
Bounces, unsubs, complaints — deduped and synced across every provider in real time. Stop re-sending to addresses three of your ESPs already rejected.
One record. Every event.
Opens in SendGrid. Clicks in Mailgun. Replies via SES. Stripe webhooks. Stitched onto one subscriber profile, in real time.
Unified subscriber timeline
Every send, open, click, reply, bounce, and webhook lands on a single profile. Your CRM, your support tool, and your AI agents read the same picture.
Analytics, not dashboards
Per-route, per-segment, per-provider metrics. Inbox placement, complaint rate, time-to-open, revenue per send. Slice by anything you tag.
Read it from anywhere. Build with it.
REST API for AI agents. Webhooks for everything else. The 30+ integrations you'd build anyway, already there.
AI agent API
Read-only REST endpoint built for LLM agents. Pull a full subscriber history, query event streams, ask for the next best action. Scoped tokens, audited every call.
Webhooks & integrations
Subscriber state changes, send events, bounces, all available as webhooks. Out of the box: Slack, HubSpot, Salesforce, Notion, Segment, dbt, Snowflake.
# Ask Senderstool what an AI agent should do next GET /v1/subscribers/marta@northwind.io/next-action Authorization: Bearer sk_agent_***** # Response { "profile": { "plan": "trial", "day": 14, "reply_count": 0 }, "signals": ["receipt_opened", "weekly_digest_engaged"], "suppress": ["reengagement_blast"], "next": { "campaign": "upgrade_offer", "via": "Postmark", "confidence": 0.82 } }
The honest answers.
Do you replace my email providers?
No. You keep them. Senderstool sits in front: routing decisions, observing health, unifying events. If you'd like us to manage providers for you (contracts, escalations, warmup), we can — ask on the call.
How do you decide which provider is "cheapest"?
We model each provider's effective price-per-message for your message types, recipient geography, and committed volume tiers. The cost engine re-runs every hour. Cheapest is always cheapest that still meets the rule — a transactional message tagged priority-high will never route to a bulk pool just because it's cheaper.
What happens if Senderstool itself goes down?
The router is multi-region with a static fallback config baked into the SDK. If the control plane is unreachable, traffic falls back to your default provider with no message loss. We've never had a full outage; this is the worst case.
Can I export everything?
Yes — subscriber records, full event history, rule configs, suppression list, analytics. CSV, JSON, or live read API. Your data is yours; we don't lock it.
Do I have to migrate everything at once?
No. Start with one message type — transactional is usually safest — prove it, then move marketing, then bulk. We pair you with the founder for the entire migration; typical end-to-end is around 2 weeks for most stacks.
Is there a free tier or self-serve signup?
Not today. Senderstool is invite-only while we're hands-on with every customer. The first month is on us while we migrate you; pricing is volume-based after that. Get in touch for a quote.
Tell us how you send today.
The founder reads every message. We'll come back with a stack review, a migration sketch, and an honest answer on whether Senderstool fits — within one business day.