How to Scale Up Cold Email Safely
Once your system is set up and getting good results, you can send more emails. Do it slowly. Sudden jumps in volume are one of the main reasons cold emails end up in spam.
Ramp up each new inbox
After warmup, don't start at the full 30 emails per day. Increase each inbox's daily campaign limit in steps, and keep warmup running alongside it:
| Week | Campaign emails per inbox, per day |
|---|---|
| Week 1 | 5 to 10 |
| Week 2 | 10 to 20 |
| Week 3 onwards | 20 to 30 |
Set the limit in Instantly under each inbox's Settings, or in the campaign's sending options.
Watch your numbers
Check these every week. If one goes into the red, slow down and fix the cause before you send more.
| Measure | Good | Take action |
|---|---|---|
| Bounce rate | Below 1% | Above 2%: pause and validate your list again |
| Spam complaint rate | Below 0.1% | Above 0.3%: pause and review your targeting and content |
| Reply rate | Above 2% to 3% | Below 1%: review your targeting and test new emails |
| Warmup health score | Close to 100% | Falling: lower the inbox's daily limit |
For Gmail recipients, sign up to Google Postmaster Tools to see your domains' spam rate and reputation.
Add more domains and inboxes
To send more, add capacity rather than pushing each inbox harder:
- Use the sending volume formula to work out how many inboxes and domains you need
- Buy the new domains and set them up as before (domains, inboxes and authentication)
- Warm up the new inboxes for at least 14 days
- Add them to your campaigns and ramp them up as shown above
It's a good idea to buy and warm up a few spare domains in advance. If one domain's reputation drops, you can rest it and switch to a spare without slowing down.