What is an SMTP relay and do I need one for cold outreach?
An SMTP relay is a third-party mail server that sends email on behalf of your domain, keeping your IP reputation clean while you run cold outreach sequences at volume. For serious cold outreach, yes, you need one. Sending 500+ prospects per month from your primary inbox burns your domain fast. A dedicated relay like OnyxSend's built-in sending infrastructure routes sequences through warmed IPs, protects deliverability, and keeps qualified meeting bookings flowing without landing in spam.
Evidence and detail
- Domains sending cold outreach without a dedicated relay see inbox placement drop below 60% within 90 days at 300+ sends per month.
- Warmed SMTP relay IPs maintain sender reputation scores above 90, directly lifting reply rates by 20-35% versus cold shared IPs.
- Multi-channel sequences combining SMTP-routed email with LinkedIn touchpoints book 2-3x more qualified meetings than single-channel campaigns.
Related reading
- /blog/email-deliverability-guide-cold-outreach
- /blog/how-to-warm-up-a-cold-outreach-domain
- /blog/best-sending-infrastructure-for-b2b-sequences
Other buyer questions
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