Email deliverability best practices and troubleshooting
updated: 2026-01-20
| Metric | Healthy | Warning | Critical |
|---|---|---|---|
| Bounce Rate | <2% | 2-5% | >5% |
| Spam Complaint Rate | <0.1% | 0.1-0.5% | >0.5% |
| Inbox Placement | >95% | 80-95% | <80% |
| Sender Score | >80 | 60-80 | <60 |
DELIVERABILITY =
Sender Reputation (40%)
+ Content Quality (30%)
+ Technical Setup (20%)
+ List Quality (10%)
| Day | Emails/Day | Total Sent |
|---|---|---|
| 1-7 | 10-20 | 70-140 |
| 8-14 | 30-50 | 280-490 |
| 15-21 | 75-100 | 805-1190 |
| 22-28 | 150-200 | 1855-2590 |
| 29+ | Scale gradually | - |
| Positive Signals | Negative Signals |
|---|---|
| Opens | Spam complaints |
| Replies | Hard bounces |
| Clicks | Low engagement |
| Forwards | Unsubscribes |
| Non-spam marking | Spam trap hits |
High-Risk Words:
FREE, GUARANTEE, WINNER, CASH, PRIZE
URGENT, ACT NOW, LIMITED TIME
Click here, Click below, Don't miss
Make money, Extra income, Work from home
Formatting Red Flags:
| Do | Don't |
|---|---|
| Plain text emails | HTML-heavy templates |
| Single link (if any) | Multiple CTAs |
| Conversational tone | Salesy language |
| Short sentences | Long paragraphs |
| Proper grammar | Typos and errors |
| Record | Purpose | Status Check |
|---|---|---|
| SPF | Authorize sending servers | nslookup -type=TXT domain |
| DKIM | Email signature verification | Check in email headers |
| DMARC | Policy for failed checks | nslookup -type=TXT _dmarc.domain |
SPF: v=spf1 include:_spf.instantly.ai ~all
DKIM: Configure via Instantly dashboard
DMARC: v=DMARC1; p=none; rua=mailto:[email protected]
| Verification Level | Description | Bounce Rate |
|---|---|---|
| Syntax check | Valid format | Reduces 5-10% |
| Domain check | Valid domain | Reduces 10-20% |
| Mailbox check | Exists | Reduces 20-40% |
| Engagement check | Active | Reduces 5-15% |
| Practice | Frequency | Impact |
|---|---|---|
| Remove hard bounces | Immediately | Critical |
| Remove soft bounces | After 3 attempts | High |
| Remove unsubscribes | Immediately | Critical |
| Re-verify list | Every 3 months | Medium |
Diagnosis Steps:
Remediation:
Possible Causes:
Diagnosis:
Immediate Actions:
Long-term:
| Day | Action | Expected Outcome |
|---|---|---|
| 1-3 | Pause all sending | Stop damage |
| 4-7 | Remove problem addresses | Clean list |
| 8-14 | Warm up from scratch | Rebuild slowly |
| 15-21 | Monitor metrics closely | Catch issues early |
| 22+ | Gradually scale | Sustainable growth |