The right cadence depends on how often you send. As a baseline: scan core deliverability metrics after every campaign, do a deeper review weekly, and run a full reputation audit at least once a month. Combine that with always-on automated blacklist monitoring and you’ll catch problems before they hurt revenue.
Quick rule: manual checks are for context, automated monitoring is for alerts. You need both.
Recommended monitoring cadence
| Frequency | What to check | Why |
|---|---|---|
| After every send | Bounce rate, complaint rate, delivery rate | Catch a bad list segment early |
| Daily | Reputation dashboards (Postmaster, SNDS) | Spot a sudden drop within 24 h |
| Weekly | Open and click rates per segment | Detect engagement decay |
| Monthly | Full deliverability audit + DNSBLs | Confirm authentication and inbox placement |
| Continuously | Automated DNSBL monitoring | Be alerted the moment IP/domain is listed |
Key metrics that signal trouble
- Bounce rate above 2% — usually a sign of dirty list or broken authentication.
- Complaint rate above 0.1% — mailbox providers will start filtering hard.
- Sudden drop in opens — emails are quietly going to spam.
- Reputation score falling on Postmaster Tools — warning before a listing.
- Click-to-open ratio collapsing — could indicate prefetching by spam filters or content blocked.
Don’t wait for a big campaign to find out: reputation problems compound. A small uptick in complaints today becomes a Spamhaus listing in two weeks if ignored.
Tools to use
Combine your ESP’s built-in stats (delivery, bounce, complaint) with external dashboards: Google Postmaster Tools, Microsoft SNDS, Talos Intelligence, and a DNSBL monitoring service.
Set up always-on monitoring today
Learn how blacklist monitoring works, run a manual blacklist verification and review the consequences of being listed so you know what you’re protecting against.