You can have the best copy in the world and a hyper-targeted list, but if your emails are landing in spam, none of it matters. Deliverability is the unsexy foundation that everything else sits on — and it's where most campaigns quietly die before anyone notices.
Never Send From Your Primary Domain
Your primary domain is a business asset. If it gets flagged for spam, your entire company's email — including customer comms, transactional emails, and internal communication — suffers. Always use dedicated sending domains for outbound. Register variations like your-company.io or yourbrand.co and configure them separately.
The Essential DNS Configuration
- SPF: Lists which servers are authorised to send email from your domain
- DKIM: Adds a cryptographic signature to verify the email wasn't tampered with
- DMARC: Tells recipient servers what to do if SPF or DKIM fails
- MX Records: Required even on sending-only domains to handle bounces properly
- Custom tracking domain: Removes shared tracking domains that damage reputation
Domain Warmup: The Right Way
A new domain has zero sending history and zero trust. Start with 5–10 emails per day per mailbox in week one, increasing by 10–20% each week. Use a warmup tool like Lemlist, Instantly, or Mailreach to automate inbox-to-inbox warmup activity. Run warmup for at least 3–4 weeks before sending any real campaigns.
Sending Limits That Don't Kill Your Reputation
Even a well-warmed domain has limits. Industry best practice is a maximum of 30–50 cold emails per mailbox per day. If you need more volume, add more mailboxes — not more emails per mailbox. Spread sends across multiple hours to mimic human behaviour, and avoid sending on weekends.
List Hygiene Is Non-Negotiable
Bounce rates above 3–5% signal to email providers that you're sending to bad data. Verify every list before sending using tools like NeverBounce, ZeroBounce, or Hunter's email verifier. Remove hard bounces immediately, and suppress unsubscribes and complaint addresses from all future sends.
Monitoring Your Reputation
Set up Google Postmaster Tools and monitor your domain reputation weekly. Check your IP against major blacklists using MXToolbox. Use a seed-list tool to track where your emails are landing — inbox, promotions, or spam — across major email clients. If inbox rates drop below 80%, pause and investigate before continuing to send.
Deliverability isn't a one-time setup. It's ongoing maintenance. Treat it like infrastructure, not an afterthought, and it becomes a competitive advantage.