How to improve email deliverability
Deliverability isn't one thing. It's the sum of authentication compliance, sender reputation, list quality, content patterns, and engagement signal. Improving deliverability requires attacking each lever in order; otherwise you're guessing.
This action plan covers the 90-day path to inbox placement above 85% on a B2B cold-outbound stack.
Before you start
- Sending domain with established history (4+ weeks)
- Access to DNS records
- Access to Google Postmaster Tools (free) and/or Microsoft SNDS
Step-by-step
- 1
Week 1: Audit authentication
Verify SPF, DKIM, DMARC are all set and passing. Use MxToolbox SuperTool for the audit. Fix any errors first, authentication breaks everything downstream.
- 2
Week 1: Pull domain reputation reports
Google Postmaster Tools (postmaster.google.com) for Gmail spam rate and compliance status. Microsoft SNDS (sendersupport.olc.protection.outlook.com) for Microsoft. Establish baseline reputation per receiver.
- 3
Weeks 2-3: List hygiene
Run verification on the full list (NeverBounce or ZeroBounce). Suppress every hard bounce, role address (info@, support@), and disposable-domain address. Re-verify lists older than 90 days.
- 4
Weeks 3-4: Suppress non-engagers
Suppress recipients with zero engagement (no opens, no clicks, no replies) in the trailing 60 days. Sustained sending to non-engagers tanks reputation.
- 5
Weeks 4-6: Volume + content normalisation
Cap daily volume at 30% of historical peak during recovery. Reduce image content, remove spam-trigger language, shorten link counts. Recovery requires reduced load.
- 6
Weeks 5-8: Engagement-driven re-warm
Send only to high-engagement segments at the reduced volume. Replies and clicks rebuild reputation. Re-introduce broader segments after 4 weeks of clean engagement.
- 7
Weeks 8-12: Gradual ramp + monitor
Increase volume 30-40% week-over-week. Monitor Postmaster Tools / SNDS for reputation trajectory. Target reputation by week 12: spam rate under 0.1% with a Compliant status (Google) / Yellow or higher (Microsoft).
Set up tracking in 2 minutes instead of 20.
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Troubleshooting
Reputation stays Low past week 8
Either authentication has a hidden issue (DMARC alignment is the most common) or volume cuts weren't aggressive enough. Drop to 10% of historical volume for 2 weeks then resume the ramp.
Inbox placement improves on Gmail but not Microsoft
Microsoft's reputation model is more IP-driven. Consider dedicated IP if volume justifies (>50K/month). Shared IP reputation has limits.
Recovery stalls; reputation goes back down on volume increase
List quality issue. Run the verification step again; high-bounce-rate sends keep damaging reputation regardless of warmup.
Frequently asked
Can I recover from a spam-folder placement penalty?
Yes, with discipline. 4-8 weeks for moderate problems, 8-12 weeks for severe. The recovery path above works on every B2B sender we've coached through it.
Should I use a dedicated IP?
Above 50K messages/month, yes. Below that, shared IP pools (Google Workspace, ESP shared pools) have better aggregate reputation than a barely-warmed dedicated IP.
How does Outsolvi help deliverability?
Two ways. Outsolvi's Deliverability Monitor checks your SPF, DKIM, DMARC, MX and PTR records and blocklists, runs placement tests, and holds sequence sends from a mailbox that isn't healthy. Graded opens also keep Apple Mail pre-fetches and scanner hits out of your engagement numbers during a re-warm.
Track real engagement, not Apple MPP noise.
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Nate built Outsolvi after watching every email-tracking tool he had ever used lie to him about opens. Outsolvi grades every open as a person or a machine, in Outlook and Gmail, so the number on the dashboard is one a rep can actually act on.
We update these pages when the underlying mechanics change. new mailbox-provider rules, new tracker behavior, new measurement gaps. The dates above are real revisions, not auto-touches.