Cold email infrastructure calculator
Work out how many sending domains and mailboxes you need for your outbound volume, without overloading any of them. Change the numbers and the results update as you type.
What you need
Warm each new mailbox for around two to four weeks before sending at full volume, and set up SPF, DKIM and DMARC on every domain. Keep cold email off your main domain.
These are planning estimates based on common practice, not guarantees of deliverability. Inbox placement also depends on list quality, content, authentication and how recipients respond.
How the numbers work
Monthly emails are your prospects multiplied by the emails in your sequence. Divide by sending days for daily volume, then by the safe limit per mailbox. Spare capacity lets you rest a mailbox whose numbers dip.
For the full setup, including DNS records and warm-up, read our cold email infrastructure guide.
How many cold emails can one mailbox send per day?
Many senders keep each mailbox to roughly 30 to 50 cold emails per day, including follow-ups, and spread volume across more mailboxes rather than pushing one hard. New mailboxes should be warmed up first.
How many mailboxes should each domain have?
Two or three mailboxes per sending domain is a common setup. It limits how much volume any single domain carries, so one problem does not affect your whole operation.
Why do I need separate domains for cold email?
Cold email always generates some bounces and complaints. Sending from secondary domains protects the reputation of your main domain, which your team relies on for everyday email.
How long does warm-up take?
Plan on around two to four weeks before sending at full volume from a new mailbox, and keep warm-up running at a low level afterwards.
Want it set up for you?
We register the domains, configure authentication, warm up the mailboxes and connect them to your prospect data.