What is a sending infrastructure for cold email?
Sending infrastructure is the technical foundation that gets cold emails into prospect inboxes instead of spam folders. It includes dedicated sending domains, warmed mailboxes, DNS records (SPF, DKIM, DMARC), and IP reputation management working together. Teams running 2,000 to 10,000 prospects per month need multiple sending domains rotating across sequences to protect deliverability. OnyxSend manages this layer automatically, so your sequences reach inboxes and generate qualified meetings without manual DNS configuration or mailbox juggling.
Evidence and detail
- Proper SPF, DKIM, and DMARC setup reduces spam placement by up to 90% compared to unconfigured domains.
- Sales teams using dedicated warmed domains see 30-50% higher reply rates versus shared or cold sending IPs.
- Multi-domain rotation across sequences lets teams scale to 10,000+ monthly prospects without inbox placement degradation.
Related reading
- /blog/how-to-warm-up-a-cold-email-domain
- /blog/spf-dkim-dmarc-setup-guide-cold-outreach
- /blog/how-many-emails-per-day-per-mailbox
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