In short
- Fix one layer at a time and re-test after each.
- DNS changes give the fastest measurable improvement.
- Cut volume while you repair — do not keep sending at full rate.
- Rebuild with your most engaged recipients first.
Day 1 — Stop and measure
- Pause scheduled campaigns.
- Pull the failure reasons from your last send and group them by receiving domain.
- Run SPF, DKIM, DMARC, and MX lookups on your sending domain.
- Record where each test stands so you can prove improvement later.
Day 1-2 — Repair DNS
Publish a single SPF record that authorises your real sending server, publish the DKIM public key for the selector your SMTP signs with, and publish a DMARC record starting at p=none with a reporting address. Wait for DNS to propagate, then re-test.
Day 2-3 — Clean the list
- Remove invalid syntax, duplicates, and role addresses you never intended to mail.
- Remove every address that previously hard-bounced.
- Segment out contacts with no engagement in 6-12 months.
Day 3 — Repair the message
- Add a plain-text alternative.
- Add a visible unsubscribe link plus unsubscribe headers and one-click support.
- Rewrite subjects that stack urgency, money claims, or ALL CAPS.
- Replace shortened links with your own domain's links.
- Fix broken or unsafe HTML.
Week 1-4 — Rebuild reputation
Send only to your most engaged segment at a modest rate, and increase gradually while bounces and complaints stay low. Keep the cadence steady — irregular bursts slow recovery. Expect weeks, not days.
Checklist
- Campaigns paused while repairing.
- SPF, DKIM, DMARC re-tested and passing.
- List cleaned and unengaged contacts segmented out.
- Plain-text and unsubscribe added.
- Volume ramped back gradually.
Run these checks now
Questions people ask
Should I change domains to escape a bad reputation?
Only as a last resort, and never as a way to keep bad habits. A fresh domain with the same list and pattern will fail the same way, and you lose whatever good history you had.
How do I know the fix worked?
Re-run the same domain checks, then send a small campaign to engaged recipients and compare accepted and failed counts against your baseline.
Does BulkMailer help with this?
Yes. It runs pre-send inbox-readiness checks, adds plain-text alternatives and unsubscribe headers automatically, and gives per-recipient SMTP responses so you can see exactly what changed. It reduces identifiable risk; it cannot guarantee placement.