📧 Email Deliverability
9 min de leitura
IP Warmup & Building Sending Reputation
How to warm up a new IP address for email sending, build a positive sender reputation, and avoid landing in spam folders.
Why Warm Up an IP?
When you start sending email from a new IP address, mailbox providers (Gmail, Outlook, Yahoo) have no history to judge your reputation. Sending a large volume immediately triggers spam filters.
IP warmup is the process of gradually increasing email volume over days or weeks to establish a positive reputation.
Warmup Schedule
A typical warmup schedule for a new dedicated IP:
| Day | Daily Volume | Notes |
|---|---|---|
| 1-2 | 50-100 | Send to your most engaged subscribers |
| 3-4 | 200-500 | Monitor bounce and complaint rates |
| 5-7 | 1,000-2,000 | Check inbox placement |
| 8-14 | 5,000-10,000 | Gradually increase |
| 15-21 | 20,000-50,000 | Continue monitoring |
| 22-30 | Target volume | Full volume if metrics are healthy |
Who to Send to First
During warmup, prioritize recipients who are most likely to engage:
- Recent openers — People who opened your emails in the last 30 days.
- Recent clickers — Even better engagement signal.
- Recent signups — Fresh subscribers are most engaged.
- Avoid inactive — Do not send to addresses that have not engaged in 6+ months.
Monitoring Key Metrics
| Metric | Healthy | Warning | Critical |
|---|---|---|---|
| Bounce rate | <2% | 2-5% | >5% |
| Complaint rate | <0.1% | 0.1-0.3% | >0.3% |
| Open rate | >20% | 10-20% | <10% |
| Spam placement | <5% | 5-15% | >15% |
# Check if your IP is blacklisted during warmup
# Use MXToolbox or command line:
dig +short 5.113.0.203.zen.spamhaus.org
# (reverse the octets of your sending IP)
# Empty = clean, 127.0.0.x = listed
Shared vs Dedicated IP
| Aspect | Shared IP | Dedicated IP |
|---|---|---|
| Volume needed | Any | 100K+/month recommended |
| Warmup needed | No (already warmed) | Yes (you build reputation) |
| Control | Low (affected by co-senders) | Full |
| Cost | Included with ESP | Additional fee |
If you send fewer than 100,000 emails per month, a shared IP from a reputable ESP (SendGrid, Postmark, Amazon SES) is usually better than a dedicated IP.
Best Practices
- Never buy email lists — they destroy reputation instantly.
- Implement double opt-in for all new subscribers.
- Process bounces immediately — remove hard bounces after first occurrence.
- Include a visible unsubscribe link — it is required by law (CAN-SPAM, GDPR) and reduces spam complaints.
- Maintain consistent sending patterns — sudden volume spikes trigger filters.