How do you gradually reintroduce colder segments?

Reintroducing colder segments:

Prerequisites:

Safe segment metrics stable for 2+ weeks

Postmaster reputation improving

No blocklist issues

Expansion process:

Add small portion of next engagement tier

Maybe 10-20% of current volume

Monitor for 3-5 sends

If stable, add more

Tiers to add:

60-day engagers first

Then 90-day engagers

180-day engagers with extreme caution

Never re-add truly cold segments

Warning signs to pause:

Open rates dropping

Complaints increasing

Postmaster reputation declining

Expansion is a privilege earned by stable metrics.

Gradually expand routes as trust rebuilds. Pull back immediately if problems emerge.