Automated warm-up schedule with daily volume ramp

Sending at full volume from a new IP or domain on day one is the single most common cause of catastrophic deliverability failure for email platforms. ISPs track the ratio of wanted-to-unwanted email per IP; a new IP sending 100,000 messages before establishing reputation triggers spam classification at Gmail, Yahoo, and Outlook simultaneously, often with blocks that take weeks to reverse. The industry-standard remediation is a 2–4 week progressive warm-up starting at dozens of sends per day and doubling every few days — enforced by code, not a spreadsheet. Without automated enforcement, a scheduled job or a marketing push will bypass any manual volume intention.

Implement a warm-up schedule as code that gates the daily send limit based on days since IP activation. The schedule must be read by the queue worker before dequeueing, not just documented:

const WARMUP_SCHEDULE = [
  { day: 1, maxVolume: 50 },
  { day: 2, maxVolume: 100 },
  { day: 3, maxVolume: 200 },
  { day: 7, maxVolume: 2_000 },
  { day: 14, maxVolume: 10_000 },
  { day: 28, maxVolume: 50_000 },
]

export function getWarmupLimit(ipStartDate: Date): number {
  const days = Math.floor((Date.now() - ipStartDate.getTime()) / 86_400_000)
  const tier = [...WARMUP_SCHEDULE].reverse().find(t => t.day <= days + 1)
  return tier?.maxVolume ?? Infinity
}

Store warmupStartDate on each SendingIp record. Before dequeueing a batch, query sentToday and abort if it would exceed getWarmupLimit(ip.warmupStartDate). Skip the warmup gating only for ESPs (SendGrid shared IPs, etc.) where the provider manages reputation on your behalf.