DNS Pre-warming Before Sending
Resolve every recipient domain before the first message leaves, and refuse to start when too few resolve — turning a confusing class of deferral into an immediate, legible failure.
Runtime state: Runs on every campaign start in the delivery engine, and the success-ratio floor genuinely aborts a start rather than warning.
- Business objective
- Never begin a send into an unknown routing picture, because the resulting deferrals look identical to throttling and get misdiagnosed hours later.
- Trigger
- A campaign start, before any message is transmitted.
- Inputs
- The campaign's recipient domain set
- Configured minimum resolution success ratio
- Whether pre-warm is required for this lane
- Outputs
- A warmed routing cache for the campaign's destinations
- A resolution success ratio measured against the floor
- Either a started campaign, or an aborted start with a specific reason
Why this exists
Deferrals caused by unresolved routing look exactly like deferrals caused by throttling. An operator sees a campaign delivering slowly, assumes the receiving provider is rate-limiting, and starts tuning concurrency — which does nothing, because the problem is that we cannot route to the destination at all.
The realization cost is hours, and it lands mid-campaign. This workflow moves the discovery to before the first message, where it costs a restart.
The workflow
Pre-warm and gate
The abort is the point. A warmed cache without a gate is an optimization; with a gate it is a safeguard.
- Automated software
Collect the campaign's recipient domains
Distinct destination domains extracted from the campaign's index.
- External service
Resolve routing records
Every distinct domain resolved concurrently, populating the routing cache.
- Automated software
Measure the success ratio
Successful resolutions as a proportion of distinct domains attempted.
- Approval gate
Compare against the configured floor
Decision point: Below the floor and pre-warm is required for this lane? Abort the start. Otherwise proceed with a warmed cache.
- Human action
Operator sees a specific reason
An explicit refusal naming the ratio, not a campaign that silently underperforms.
- Automated software
Delivery starts with warm routing
Workers resolve from cache rather than paying lookup latency on the first message to each destination.
- Human action
- Automated software
- External service
- Approval gate
Decision points
- Is pre-warm required for this lane? Configured per lane, because a lane sending to a small, well-known destination set has different risk from one sending broadly.
- Is the success ratio above the floor? The single gate. Below it, the start is refused.
Responsibilities
AI / LLM
- Nothing. No model participates in this workflow at any point.
Deterministic
- Domain extraction and deduplication.
- Concurrent resolution and cache population.
- Success ratio calculation.
- The floor comparison and the abort decision.
Human approval points
- Configuring the floor and whether pre-warm is required for a lane.
- Deciding what to do after an abort — investigate the domain set, or proceed with pre-warm disabled for a lane where that is genuinely appropriate.
Failure handling
| Failure | Response |
|---|---|
| Individual domain fails to resolve | Counted against the ratio; the campaign is not blocked by one bad domain. |
| Success ratio below the floor | Abort the start with the measured ratio in the message. |
| Resolver itself unavailable | Ratio collapses, gate aborts. Correct behavior — we genuinely cannot route. |
| Pre-warm not required for the lane | Cache is still warmed; the gate does not abort. |
Monitoring
Resolution success ratio per campaign start, abort count and reason, cache hit rate during delivery, and resolution latency. A rising abort rate is a signal about list quality, not about the resolver.
Business value
Converts a slow, ambiguous failure that costs hours of misdiagnosis into an immediate one with an obvious cause. The cheapest incident is the one that never starts.
Related projects
Related workflows
- Campaign Creation to Delivery
From an operator composing a campaign to messages accepted by receiving providers, through a single mandatory suppression gate and a fail-closed readiness barrier.
- Closed-Loop Throughput Tuning
Adjust delivery concurrency from smoothed per-destination outcomes rather than from static configuration — with ceilings a loop can never exceed.