Lapsed subscribers cost you reputation and money. A good re-engagement campaign either reactivates them or removes them cleanly.
Define lapsed. No open or click in 90 days is a defensible baseline. Adjust for your sending cadence.
Segment by depth of lapse. 90-180 days, 180-365 days, 365+ days. Send different content to each. The longest-lapsed cohort needs the most direct call to action.
Three-touch sequence. First email: "We miss you." Second (5 days later): single-question survey on what they want. Third (5 days later): clear unsubscribe option presented as a choice, not a punishment.
Win-back content. Lead with the value you have added since they last engaged. If you have new features, this is where to mention them.
Suppress aggressively at the end. Anyone who does not engage with the sequence should be removed from active sending. Continuing to send to non-engaged subscribers actively damages your inbox placement for everyone else.
Measure with the right baseline. Re-engagement open rates of 5-15% are normal. Anything higher is great. Compare to your baseline lapsed rate, not your active rate.