Sending volume
How Many Mailboxes Do You Need for Cold Email?
Estimate mailbox requirements with daily capacity, sequence demand, send windows and a buffer for interruptions.
Divide required daily sends—including follow-ups—by the conservative daily capacity you assign to one mailbox, then add operating headroom. For 150 daily sends at 30 per mailbox, five mailboxes is the mathematical minimum; six gives useful buffer.
Use the capacity formula
Mailboxes needed = required daily campaign sends ÷ configured sends per mailbox, rounded up. Do not start with lead count alone because sequences create additional sends over time.
Example: 900 prospects entering a three-step sequence over 15 sending days can create up to 2,700 sends. That averages 180 per day before replies reduce demand. At 30 per mailbox, the baseline is six mailboxes.
Add headroom
Exact-capacity plans are fragile. A disconnected mailbox, provider throttle, holiday or reply spike can delay the whole schedule. Ten to twenty percent headroom is a planning buffer, not a deliverability promise.
- Model first touches and follow-ups separately.
- Respect plan-level monthly allowance too.
- Exclude paused or unhealthy mailboxes.
- Recalculate when reply and stop rates become known.
More mailboxes are not always better
Every mailbox needs setup, monitoring and reply coverage. Use the smallest well-managed pool that meets measured demand. Paid MailQV plans allow unlimited mailbox connections, while workspace quotas and mailbox controls still apply.
Put it into practice
Run measured outreach with mailbox-level control.
MailQV connects sender rotation, sequences, contacts and campaign signals without claiming guaranteed inbox placement.