Cloud Server for Email
cloudserverforemail.com · infrastructure@cloudserverforemail.com · +372 602 3545
EU-Based Infrastructure
Operating Since 2015
Operating Since 2015
Email List Hygiene Best Practices
Maintaining List Quality for Consistent Inbox Placement
Version 2026-04 · Cloud Server for Email
List Quality Metrics Dashboard
| Metric | Healthy | Review | Critical |
|---|---|---|---|
| Hard bounce rate (per campaign) | <0.5% | 0.5–2% | >2% |
| Spam complaint rate | <0.05% | 0.05–0.10% | >0.10% |
| Unsubscribe rate | <0.3% | 0.3–0.5% | >0.5% |
| 30-day open rate | >25% | 15–25% | <15% |
| Inactive subscribers (>180d) | <20% | 20–40% | >40% |
| Invalid addresses (bounced) | <1% of list | 1–5% | >5% |
Acquisition Hygiene
- Real-time email validation at opt-in: syntax check + domain/MX verification
- Double opt-in for all consent-based B2C sending (strongly recommended for EU)
- Honeypot field in all sign-up forms (catches bots)
- Source tracking: record where each subscriber came from (web form, API, import)
- No purchased, rented, or scraped lists
- Verify any third-party lists with an email validation service before first send
Ongoing Bounce Processing
- Hard bounces: suppress immediately on first occurrence, within 24 hours
- Soft bounces: suppress after 3 consecutive soft bounces to same address
- Role addresses (postmaster@, abuse@, noreply@): suppress or exclude
- Abuse@, postmaster@, role@ addresses: never email these
- Run bounce-handler cron every 2 minutes (MailWizz)
Engagement-Based Suppression Schedule
| Last Engagement | Segment | Action |
|---|---|---|
| 0–30 days | Active | Send at full frequency |
| 31–90 days | Warm | Send at normal frequency; monitor engagement |
| 91–180 days | Cooling | Reduce frequency by 50%; trigger re-engagement sequence |
| 181–365 days | Inactive | Pause regular campaigns; send final win-back |
| 366+ days | Lapsed | Suppress from all campaigns |
Re-Engagement Campaign Template
- Subject: "We miss you — still interested in [topic]?" (personalized)
- Content: Brief reminder of value; clear CTA to confirm interest
- CTA: "Yes, keep sending me updates" (explicit re-consent)
- Secondary CTA: "Unsubscribe" (make it easy to leave)
- Timing: Send to 91–180 day inactives; suppress non-openers after 14 days
- Do not: Send multiple re-engagement emails to the same address
List Validation Before Major Sends
- If list has not been mailed in 90+ days: run through email validation service
- Remove all hard bounces and spam complaints before sending
- Validate: syntax, domain/MX existence, catch-all detection, spam trap detection
- Tools: ZeroBounce, NeverBounce, Mailgun Validation, BriteVerify
- Accept only addresses with "valid" or "catch-all" status; reject "invalid" and "disposable"
The single most impactful list hygiene practice: suppress all subscribers with no opens or clicks in the past 180 days before any high-volume campaign. This alone typically reduces complaint rates by 40–60% on lists with poor historical hygiene.