What’s a customer milestone (anniversary, renewal, upgrade) flow?

A milestone flow triggers automated emails when customers reach significant moments in their relationship with your brand:

Anniversary emails celebrating one year (or more) since first purchase or signup. Often include thank-you messages and special offers.

Renewal reminders for subscription products, alerting customers before auto-renewal or prompting manual renewal action.

Upgrade prompts when customers reach usage thresholds or tenure that suggests readiness for premium tiers.

Achievement celebrations recognizing loyalty program milestones, purchase thresholds, or engagement accomplishments.

Milestone emails typically see high engagement because they feel personal and recognize the customer's history.

Milestones acknowledge that relationships have history. Celebrating them shows customers you value the journey, not just the transaction.