Warm-Up Best Practices Guide
Why Warm Up?
New sending domains and IPs have no reputation history. Mailbox providers (Gmail, Outlook, Yahoo) use reputation to decide whether to deliver to inbox or spam. Sending high volume from an unknown domain signals spam.
Warm-up gradually increases volume over days/weeks, allowing providers to observe positive engagement signals (opens, clicks) and build trust.
Recommended Warm-Up Timeline
| Day | Suggested Volume | Notes |
|---|---|---|
| 1-3 | 50-200 | Send to your most engaged contacts first |
| 4-7 | 200-1,000 | Monitor bounces and complaints daily |
| 8-14 | 1,000-5,000 | Check Google Postmaster Tools for reputation |
| 15-21 | 5,000-20,000 | Gradually increase if metrics are healthy |
| 22-30 | 20,000+ | Approach full volume, continue monitoring |
These numbers are guidelines — actual volumes depend on your list size and target volume.
Warm-Up Strategies in EmailElement
Linear
- Adds a fixed number of emails per day
- Example: start 100, increment 200 → Day 1: 100, Day 2: 300, Day 3: 500
- Best for: predictable, steady ramp-up
- Configure: set Base Volume and Increment Per Day
Exponential
- Increases by a percentage each day
- Example: start 100, grow 50% → Day 1: 100, Day 2: 150, Day 3: 225, Day 4: 337
- Best for: faster ramp-up that mirrors natural growth curves
- Configure: set Base Volume and Increment Percentage
Custom
- Manually set the volume for each individual day
- Best for: specific requirements from an ESP or deliverability consultant
- Configure: edit each day's volume in the warm-up plan editor
Setting Up a Warm-Up in EmailElement
- Navigate to Schedule > click Create Scheduled Email
- Select your Email Content, Segments, and Send Integration
- Under Schedule Recurring, select Warm-up as the frequency
- Configure:
- Start Date — when to begin
- Number of Days — warm-up duration
- Start Time / End Time — daily sending window
- Base Volume — starting daily volume
- Strategy — Linear, Exponential, or Custom
- Increment — fixed number (Linear) or percentage (Exponential)
- Click View/Edit Warm-up Plan to review the day-by-day schedule
- Adjust individual days if needed (Custom strategy or manual overrides)
- Click Save Warm-up Schedules
During Warm-Up
Monitor Daily
- Check Delivery Events for bounce and complaint rates
- Hard bounce rate should stay under 2%
- Complaint rate should stay under 0.1%
- If either spikes, pause the warm-up immediately
Send to Engaged Contacts First
- Warm-up automatically prioritizes contacts not emailed in the last 60 days
- Create a Segment of your most engaged contacts (opened or clicked in last 30 days) for the initial phase
- Expand to broader segments as reputation builds
Use Volume Caps
- Set Volume Caps on your Send Integration to control hourly send rate
- This prevents bursts that trigger rate limiting at the ESP or recipient servers
Don't Skip Days
- Consistent daily sending builds a positive reputation pattern
- Gaps in sending reset momentum and can hurt reputation
Troubleshooting During Warm-Up
| Issue | Action |
|---|---|
| High bounce rate (>2%) | Pause warm-up. Clean your list — remove invalid addresses. Resume with lower volume. |
| High complaint rate (>0.1%) | Pause warm-up. Review content — ensure clear unsubscribe link and relevant content. |
| Emails going to spam | Check authentication (SPF, DKIM, DMARC). Check Google Postmaster Tools for reputation. Reduce volume. |
| ESP rate limiting | Lower Volume Caps. Spread sends over a longer time window (extend Start Time to End Time range). |
| Warm-up stalled | Check if the Scheduled Email is paused. Check Send Integration status. Review Delivery Events for errors. |
After Warm-Up
- AllWarmupComplete flag indicates all warm-up scheduled emails have finished
- Transition to regular sending using normal Scheduled Email (not warm-up frequency)
- Continue monitoring bounce and complaint rates
- Maintain consistent sending volume — don't suddenly spike after warm-up