Which of your domains are burning?

Why burning domains look healthy in your sequencer

A domain rarely dies all at once. It slides: warmup emails start landing in spam, then bounces creep up, then replies thin out — and the campaign dashboard averages it all away until the domain stops working entirely. By the time anyone asks why reply rates dropped, the domain has usually been burning for weeks. This checker reads the signals the dashboard buries: per-mailbox error states, warmup spam placement, and the contradiction between a green warmup score and where the mail actually lands.

The signals behind each verdict

Mailbox error states

Connection, bounce or sending failures reported by the sequencer itself. Any mailbox in one of these states marks its domain burnt — the provider has already stopped delivering its mail.

Warmup spam placement

The earliest burn signal there is. Warmup emails landing in spam at 5% or more puts a domain at risk; 10% or more is a burn. These are the same thresholds ColdOps alerts on in production.

The lying warmup score

A warmup score of 85+ while warmup mail lands in spam means the score is grading the tool's own test traffic, not your reputation. The report calls this out explicitly, because it's the number agencies wrongly trust the longest.

A burn check vs domain burn alerts

This page is a snapshot — useful, but a domain that is healthy today can be burning in two weeks, and a check you have to remember to run is a check that runs late. Continuous domain burn alertswatch the same signals after every sync and email you the day the trend turns, which is the difference between resting a domain and replacing it. That's the product version of this tool: it also catches blacklistings, bounce spikes past the 2% danger line and reply-rate crashes, and can pause burning mailboxes automatically. If a domain here came back burnt, the re-warming guide covers the rest-or-replace decision.

Common questions

What is a burnt domain?

A sending domain whose reputation has degraded to the point that mailbox providers filter most of its mail to spam. In practice it shows up as mailboxes entering error states, warmup emails landing in spam, bounce rates climbing and replies drying up — often while the sequencer's own dashboard still looks normal.

Is my API key stored?

No. The key is used for one read-only request to your sequencer's API, the report is computed in memory, and the key is never written to a database, a log, or anywhere else. The check never sends an email or changes a setting.

Which sequencers does it support?

Instantly, Smartlead and EmailBison. One note on Smartlead: its API reports connection failures but not bounce or sending error states, so Smartlead verdicts lean more on warmup spam placement. EmailBison is self-hosted, so the checker also asks for your workspace URL.

Can a burnt domain recover?

Sometimes, if you catch it early. Pause sending, fix the cause (usually list quality or volume), and re-warm for two to three weeks before retrying at lower volume. A domain that keeps landing in spam after a full re-warm is usually cheaper to replace than to rehabilitate.