Warm-Up & Mailbox Calculator
Sending 500 cold emails a day from one mailbox is how domains get burned. Tell us your target volume and how old your domains are, and get the number of mailboxes and domains to spread it across - plus a week-by-week ramp.
Your setup
Week 1 is warm-up only, then cold volume ramps up over four weeks.
Week-by-week ramp
| Week | Phase | Cold / mailbox / day | Warm-up / mailbox / day | Total cold / day |
|---|---|---|---|---|
| 1 | Warm-up only | 0 | 5 | 0 |
| 2 | Ramping up | 10 | 10 | 130 |
| 3 | Ramping up | 20 | 15 | 260 |
| 4 | Ramping up | 30 | 20 | 390 |
| 5 | Full volume | 40 | 20 | 500 |
After week 5, hold warm-up running at about 20 a day per mailbox - stopping it is one of the most common ways a healthy mailbox starts slipping to spam.
These are conservative planning numbers from what works in practice, not limits set by Google or Microsoft - they don’t publish any. Watch your bounce rate (keep it under 2%) and back off at the first sign of spam placement.
Would rather not buy, configure and warm up dozens of mailboxes yourself? We build and run the whole sending infrastructure.
How we help: Consulting · Private infrastructure · Managed mailboxes · Monthly support