A large dormant list looks like an opportunity and behaves like a liability. These are people who consented long ago, have not interacted since, and may not remember you at all — which is exactly the profile that produces blocks.
Understand the risk before sending
Blocks from a dormant campaign feed quality rating, quality rating governs your limits, and limits govern your ability to send anything at all. A badly judged reactivation campaign can degrade your transactional messaging for weeks. That asymmetry should shape everything about how you run one.
Segment dormancy by degree
- 3–6 months — likely still remember you. Reasonable to message normally.
- 6–12 months — approach carefully, lead with identity.
- 12+ months — treat as cold. Re-permission rather than market.
- Never engaged at all — the highest risk group in your database. Many should simply be removed.
Send in small batches and watch. Take the first 200, send, and look at the block rate before sending to the next 200. If it is materially above your normal, stop — you have learned something cheaply instead of expensively.
Lead with who you are
The first line must remove the "who is this?" question, because that question is what produces a block. Name the business, and give a specific reminder of the relationship.
Works: "Hi Priya — this is Northline, where you bought a pair of running shoes last March. We have not been in touch in a while."
Does not: "We miss you! Here's 20% off." — no identity, no context, and an offer from a stranger.
Ask permission rather than assuming it
For genuinely cold contacts, the honest move is to make the message about whether they still want to hear from you. It feels like it sacrifices reach, and it substantially reduces blocks, because you have handed control back.
"If you would still like occasional updates from us, reply YES. If not, reply STOP and we will not message again." Those who reply YES are worth far more than the silent majority you would otherwise keep paying to message.
Give a reason for the gap
If something has genuinely changed — a new range, a location, longer opening hours — say so. It explains why you are writing now, which is a question the recipient is implicitly asking. A message with no occasion reads as list-mining.
One attempt, then decide
Do not run a three-message reactivation series at people who have ignored you for a year. Send one, wait a fortnight, and split the list: those who engaged return to your active audience; those who did not should be suppressed from marketing permanently.
Deleting non-responders feels like destroying an asset. It is not — they were never an asset. They were a cost with a quality-rating risk attached, and removing them improves every metric you have.
Prevent dormancy instead
The best reactivation programme is not needing one. Contacts go quiet because messaging stopped being relevant or became too frequent. Watching engagement decay by segment, and adjusting before people disengage entirely, is cheaper and considerably less risky than winning them back.