Email Warm-Up
The process of gradually increasing email volume from a new IP or domain to build sender reputation and avoid spam filters that hurt deliverability.
Definition
Email warm-up involves sending progressively larger batches of email from a new sending infrastructure to establish trust with ISPs. Starting with small volumes to engaged subscribers, then slowly scaling up.
This process typically takes 4-8 weeks depending on target volume, with careful monitoring of bounce rates and spam complaints.
Why It Matters
Sending large volumes from a cold IP triggers spam filters. ISPs treat unknown senders as suspicious until proven legitimate through consistent positive engagement.
Rushing the warm-up process can permanently damage a new IP's reputation, requiring expensive infrastructure changes.
Examples in Practice
A company migrating email platforms starts sending 500 emails daily to their most engaged subscribers. They increase volume 20% every few days while maintaining under 2% bounce rates, reaching full volume after 6 weeks.
A new business begins cold outreach at 50 emails per day, adding 25 more daily only when replies exceed 10% and spam complaints stay under 0.1%.