Why New Domains Need Warmup
Email providers assign a sender reputation score to every domain that sends email. New domains start with a neutral or cold reputation, meaning providers are cautious about delivering their messages. Gmail processes over 300 billion emails daily (Google Transparency Report 2024), and its spam filters rely heavily on domain history to separate legitimate senders from spammers. Warmup builds that history through controlled, positive interactions.
The warmup process works by:
- Sending small volumes — starting with 5-10 emails per day from each inbox
- Generating engagement — warmup emails are opened, read, and replied to by real inboxes
- Gradually increasing volume — daily sends increase by 10-20% as positive signals accumulate
- Rescuing spam placement — warmup partners move emails from spam to inbox, sending a positive signal to the provider
Warmup Best Practices for Recruitment Agencies
Australian recruitment agencies should warm up each outreach domain for at least 14 days before launching campaigns. Best practice is to use a separate domain for outreach (e.g. outreach.youragency.com.au) rather than your primary business domain, so any reputation issues from cold emailing do not affect internal communications or client correspondence.
Automated vs Manual Warmup
Approaches to domain warmup:
- Automated warmup networks — platforms exchange emails between real inboxes in a pool, generating natural engagement patterns without manual effort
- Manual warmup — sending real emails to contacts you know and asking them to reply, which works but does not scale
- Dedicated warmup services — standalone tools like Warmup Inbox or Mailreach that charge A$15-30 per inbox per month
- Built-in warmup — CRM platforms like Kolvera include warmup as part of the mailbox management system at no extra cost
Key warmup metrics to monitor include inbox placement rate (target 95%+), spam rate (target under 1%), bounce rate (target under 2%), and per-provider delivery rates for Gmail and Microsoft 365 separately.