IP Warmup

IP warmup is the process of gradually increasing sending volume from a new IP address so that receiving mail servers build trust in your sender reputation. Starting at low volumes and ramping up over 30–60 days significantly reduces the risk of landing in spam folders.

Why warmup matters

New IP addresses have no sending history. If you immediately send 100,000 emails from a fresh IP, inbox providers will likely block or bulk-folder your messages. A structured warmup schedule builds a positive reputation signal over time.

Typical warmup ramp:

Get warmup report

GET /api/warmup

Returns the current warmup state for all tracked IPs plus a pool-level capacity summary.

Response

{
  "success": true,
  "ips": [
    {
      "ip_address": "198.51.100.42",
      "domain": "mail.example.com",
      "pool_name": "transactional",
      "status": "warming",
      "daily_limit_today": 2000,
      "sent_today": 847,
      "progress_pct": 42
    }
  ],
  "pools": {
    "transactional": { "pool": "transactional", "remaining": 1153, "capacity": 2000 },
    "marketing":     { "pool": "marketing",     "remaining": 4200, "capacity": 5000 },
    "cold":          { "pool": "cold",           "remaining": 0,    "capacity": 0   }
  },
  "summary": {
    "totalIPs": 1,
    "warming": 1,
    "active": 0,
    "paused": 0,
    "totalCapacityToday": 7000
  }
}

progress_pct is the percentage of today's sending window already used.

Initialize an IP for warmup

POST /api/warmup
Content-Type: application/json

Request body

Response

{
  "success": true,
  "config": {
    "ip_address": "198.51.100.42",
    "domain": "mail.example.com",
    "pool_name": "transactional",
    "status": "warming",
    "daily_limit_today": 50,
    "started_at": "2025-06-14T00:00:00Z",
    "target_daily_limit": 50000
  }
}

HTTP 201 Created.

Pause or resume an IP

PUT /api/warmup
Content-Type: application/json

{ "ipAddress": "198.51.100.42", "action": "pause" }

{ "success": true, "message": "IP warmup paused" }

Remove an IP from warmup tracking

DELETE /api/warmup?ip=198.51.100.42

Removes the IP from warmup tracking. The IP remains in its sending pool but is no longer subject to daily ramp limits. Use this when an IP has completed warmup and is operating at full capacity.

IP pool types

Example: start a warmup

curl -X POST /api/warmup \
  -H "Content-Type: application/json" \
  -d '{
    "ipAddress": "198.51.100.42",
    "domain": "mail.example.com",
    "poolName": "transactional",
    "targetDailyLimit": 50000
  }'

const res = await fetch('/api/warmup', {
  method: 'POST',
  credentials: 'include',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    ipAddress: '198.51.100.42',
    domain: 'mail.example.com',
    poolName: 'transactional',
    targetDailyLimit: 50000,
  }),
});
const { config } = await res.json();
console.log(`Warmup started. Today's limit: ${config.daily_limit_today}`);