Nine free tools to size, set up and troubleshoot cold email infrastructure. They run in your browser, with no signup and no email address required.
Size your cold email operation before you spin up inboxes.
Enter your daily cold email target and get the mailboxes, domains, Winnr plan and monthly cost you need, compared with Google Workspace and Microsoft 365.
Use toolHow many domains do you need? Set your daily volume and mailboxes per domain, and the calculator sizes your domain portfolio.
Use toolA day-by-day ramp for every new mailbox, from the first warming emails to full cold volume.
Use toolCheck a domain in one pass, then generate and validate the three records every cold email domain needs: SPF, DKIM and DMARC.
Enter a domain or email address and check MX, SPF, DKIM, DMARC, nameservers, website and BIMI records at once, with plain-language fixes.
Use toolBuild a correct SPF record from your sending sources (Google Workspace, Microsoft 365, SendGrid, Mailgun, Amazon SES and more). Also checks any existing domain's SPF.
Use toolGenerate an RSA keypair in your browser. The public key becomes a DNS TXT record and the private key stays on your device. Uses WebCrypto, so keys never touch a server.
Use toolGenerate a DMARC policy with your policy strength, rollout percentage, and reporting addresses. Also validates existing DMARC records against 2026 best practice.
Use toolQuery any DNS record type (A, MX, TXT, CNAME, NS, SOA, CAA, PTR and more) for any domain over DNS over HTTPS, with TTLs, DNSSEC status and shareable result links.
Use toolMake your cold email copy land in inboxes, not spam.
When you're ready to send, Winnr's plans give you SMTP/IMAP mailboxes with DNS set up for you, and pre-warmed mailboxes are ready to send the same day.
Winnr Startup is $69 a month for 50 mailboxes, with SPF, DKIM and DMARC set up automatically and built-in warming at $0.60 per mailbox per month.
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