Free tools
Mailbox Capacity Planner
How many mailboxes you need given a daily cap and unique contacts. These tools run in your browser. They are educational — not a substitute for mailbox warmup and clean lists.
Mailboxes needed
About 4 mailboxes if every contact gets one email.
How to use this
How many mailboxes you need given a daily cap and unique contacts.
Then do the real work in RangeLeads
Authenticate a sending domain, warm mailboxes, import a defensible list, and run a short sequence. A calculator will not fix a burned domain.
FAQ
Is this really free?
Yes. No account required for the calculators.
Do you store what I type?
These widgets run client-side. Do not paste customer PII into a public page if your policy forbids it.
Will this make me land in inbox?
No tool on the public internet can promise that.
Keep reading
Send from inboxes you control
14-day trial · 200 unique contacts · Google, Microsoft, or SMTP.