Free Tools / Mailbox Calculator
Cold Email Mailbox Calculator
Figure out exactly how many mailboxes and domains you need for your outreach volume - safely, without burning your sender reputation.
Your outreach volume
200
Total prospects you want to reach daily
3
Follow-up steps per prospect (1 = cold email only)
21
Recommended: 21 days for new domains
What you need
Emails to send per day600
Sending mailboxes needed24
Domains needed8
Warmup emails (total)7,560
Safe daily cap per mailbox25 emails
Rule of thumb
Max 3 mailboxes per domain. Max 25 cold emails/day per mailbox after warmup. Never send from your main domain.