Monitor & protect deliverability
Click-by-click: test inbox placement, set up Postmaster Tools, watch blacklists & health thresholds, and recover when reputation drops.
Authentication and warmup get you into the inbox. Staying there — across hundreds of sends a day and multiple clients — is an ongoing job. "Delivered" isn't "inbox": mail can be accepted and silently filed in spam. This guide is how you measure inbox placement and catch a reputation slide before it kills your reply rate. Click-by-click below.
On Scrupp sending inboxes a deliverability agent monitors placement, reputation and spam signals around the clock and auto-adjusts volume before problems spread. The steps below are the manual monitoring routine for when you run your own inboxes — worth understanding either way.
The mindset: deliverability isn't a one-time setup, it's a vital sign. Check it weekly per domain, and immediately whenever reply rate drops.
Step 1 — Meet the 2024+ bulk-sender rules
Google and Yahoo now enforce hard requirements for anyone sending at volume. Miss these and you're filtered regardless of warmup:
- SPF + DKIM + DMARC all passing (you set these up in the auth guide). DMARC is now mandatory, not optional.
- One-click unsubscribe (List-Unsubscribe header) and honoring opt-outs within 2 days — good sequencers add this automatically.
- Spam-complaint rate under 0.3% — and realistically you want it under 0.1%. This is the single number that gets domains throttled.
Step 2 — Test inbox placement before you launch
- mail-tester.com — send one email to the address it gives you; aim for 10/10. It flags broken auth, spammy content and missing records.
- Seed/placement test (GlockApps, or a manual seed list of Gmail/Outlook/Yahoo addresses you own) — send your real first email and check where it actually lands: Inbox, Promotions or Spam. Promotions on Gmail is a yellow flag for cold outreach; Spam means stop and fix.
- Re-run after any change to copy, volume or domains.
Step 3 — Turn on Google Postmaster Tools
- Go to postmaster.google.com, add your sending domain and verify it with a TXT record (same place you added SPF/DKIM).
- After a few days of sending it shows domain reputation (aim for High/Medium), spam rate (keep the line near zero) and authentication pass rates.
- Check it weekly. A reputation drop here is your earliest warning — earlier than reply rate.
Step 4 — Watch for blacklists
- Run your sending domain (and its IP) through mxtoolbox.com/blacklists periodically.
- If you're listed (Spamhaus, Barracuda, etc.), pause sending from that domain, fix the cause (usually bad list or volume spike), and use the blacklist's delisting form.
Step 5 — Know your health thresholds
- Bounce rate: keep under 2–3%. Higher means your list isn't clean — send only to Scrupp-verified addresses.
- Spam-complaint rate: under 0.1%. Above that, cut volume and review copy/targeting.
- Reply rate: your canary. A sudden drop with the same copy usually means placement slipped, not that the message got worse.
- Open tracking: consider sending without open-tracking pixels — they can hurt placement and inflate nothing useful.
Step 6 — When deliverability drops, the recovery playbook
- Pause sends from the affected inbox/domain — don't keep digging the hole.
- Re-verify auth (SPF/DKIM/DMARC all PASS) and check Postmaster reputation + blacklists.
- Cut volume on every inbox and turn warmup back up for ~1 week to rebuild trust.
- Clean the list — purge anything unverified; bad data is the usual root cause.
- Vary the copy — identical mass sends trip filters; use spintax and segment-specific messaging.
- If a domain is badly burned, retire it and rotate in a fresh warmed domain. This is why you keep a small bench of sending domains.
The whole game in one line: verified lists + passing auth + warm inboxes + modest volume + weekly monitoring = inbox placement. Drop any one and your reply rate quietly collapses — monitoring is how you notice before your client does.