# Scheduling & Timing

## Campaign duration

| Setting | Value |
|---------|-------|
| Recommended | 30–45 days |
| Minimum | 14 days (not recommended for new domains) |
| Maximum | 45 days (MVP cap) |

`endsAt = startedAt + durationDays`

## Daily send distribution

### Send windows

Avoid off-hours sends that signal automation.

| Parameter | Default |
|-----------|---------|
| Timezone | Campaign or mailbox TZ |
| Window start | 08:00 |
| Window end | 18:00 |
| Weekends | Optional: reduce volume 50% or pause |

### Jitter between sends

| Parameter | Default | Rationale |
|-----------|---------|-----------|
| Min gap | 45 minutes | Avoid burst patterns |
| Max gap | 180 minutes | Stay within daily quota |
| Distribution | Uniform random | Human-like variance |

```
nextSendAt = lastSendAt + random(45min, 180min)
if nextSendAt outside window: roll to next window start
```

## 48-hour volume cap

Industry guidance: never increase average daily volume more than **20% in 48 hours**.

```typescript
function cap48hIncrease(history: number[], proposed: number): number {
  const avg48h = average(last48h(history));
  return Math.min(proposed, Math.ceil(avg48h * 1.20));
}
```

Applies to all recipes except explicit expert override in Custom (with warning).

## Cron vs queue architecture

### Current (MVP)

- `node-cron` fires dispatcher every 15 min
- All eligible sends in one batch

### Target

| Component | Role |
|-----------|------|
| Scheduler cron | Every 5 min: enqueue due sends |
| Send queue | BullMQ / pg-boss / SQLite queue |
| Worker | One send per job with jitter |
| Rescuer cron | Every 10 min: IMAP scan per mailbox |

Benefits: precise timing, backoff, idempotency keys, pause per campaign.

## Campaign day rollover

At midnight (campaign TZ):

1. Increment `currentDay`
2. Load `DailySchedule` for new day
3. Reset `actualSends`, `actualReplies` counters
4. If `currentDay > durationDays` → complete or maintenance mode

## Maintenance mode (post-campaign)

After primary campaign completes:

- Continue Flat recipe at **20% of maxEmailsPerDay**
- Keeps engagement signals during live cold outreach
- Operator can disable

## Timezone handling

- Store all timestamps UTC in DB
- Display in campaign timezone in UI
- Send windows evaluated in campaign timezone