Email Warm-Up
Last updated: March 2025
Definition
Gradually increasing your email sending volume from a new or cold domain so inbox providers trust you. You start with 5-10 emails per day to engaged contacts, then slowly ramp up over two to four weeks. Skipping warm-up is the fastest way to land in spam from day one.
Why It Matters
ISPs like Gmail and Outlook monitor new senders closely. A brand-new domain blasting 500 emails on day one screams spam. Warm-up builds a sending reputation so your real campaigns actually reach inboxes. Most deliverability disasters start with skipped or rushed warm-up.
How to Improve
- Send to your most engaged contacts first during warm-up. Opens and replies signal to ISPs that people want your mail.
- Increase volume by 20-30% every few days, not all at once. Patience here saves months of deliverability repair later.
- Use a warm-up tool that automates sending and engagement with a network of real inboxes.
- Monitor bounce rates during warm-up. If bounces spike above 3%, slow down and clean your list before continuing.