How old can contacts be for a reactivation?

As a rule of thumb, contacts from the last three to five years are well usable. With older data, undeliverability and contact-person turnover rise sharply; then data enrichment and validation before sending pay off.

How many contacts do I need for a reactivation campaign?

From a few hundred relevant contacts upward, a systematic process pays off. Below that, you can call through the list manually faster than you can set up a campaign.

Should I just include undeliverable addresses in the send?

No. High bounce rates damage your sender reputation and with it the deliverability of all future emails. Validate addresses before sending and remove hard bounces.

What do I do with contacts that have no email address?

Enrich them (e.g. via data providers) or move them into a separate phone/LinkedIn track. For the first email run, only contacts with a valid address count.

Guide · Customer reactivation

Reactivate old CRM contacts: Who to write to first

Last updated: 5 October 2026 · 3 min read

"We have thousands of contacts in the CRM" sounds like a treasure, but at first it is just a number. Between the raw database and a campaign that produces replies lies exactly one task: figuring out who you write to, and who first.

This article takes you from the unfiltered CRM export to a prioritized shortlist. What to write to these contacts is covered in Reactivate customers by email; the full picture lives in the customer reactivation guide.

Step 1: Take inventory

Export the complete database (contacts, companies, deals) and answer four questions:

How many contacts are there really? After deduplication, the number is often much smaller than assumed.
How old are they? Last contact, last purchase, last quote; per contact, the most recent date.
What do you know about them? Is there an email, a contact person, deal history, a reason for the lost deal? Or just a company name?
Where do they come from? Former customers, quote recipients, trade-fair leads and newsletter signups are completely different starting points.

The result is an honest inventory instead of a ballpark figure. You do not need more at this point; no BI dashboards, a spreadsheet is enough.

Step 2: Exclusion criteria

Before you prioritize, remove everything that must not or should not be contacted:

Active customers: they belong in account management, not in a reactivation campaign
Objections and unsubscribes: anyone who objected to outreach stays out. No exceptions.
Hard bounces and obviously dead addresses: protects your sender reputation
Competitors and dead records with no realistic potential
Contacts without a legal basis for promotional emails: for existing customers, Section 7(3) of the German UWG applies under certain conditions; when in doubt, leave them out or get legal review (this article is not legal advice)

Step 3: Assess contact quality

For everything that remains: quality beats quantity. Three dimensions decide:

Dimension	Good	Critical
Recency	contact < 3 years	> 5 years, contact person probably gone
Depth	deal history, known contact person, lost-deal reason	only company name + generic inbox
Fit	matches your current ICP	industry/size no longer fits the offer

Contacts with weak quality are not worthless; they need data enrichment before sending: research current contact persons, validate email addresses, refresh company data. That costs a few cents to euros per contact and lifts the reply rate noticeably.

Step 4: Prioritize into a shortlist

Now the sorting. The most robust logic for the first run:

Former customers with repurchase logic: maintenance due, consumables, expandable project. Highest reply and close probability.
Lost deals from the last 24 months: the interest was real; often only timing or budget was missing.
Former customers without a direct reason: they know you but need a good hook.
Old leads with recognizable fit: the largest group, the lowest individual probability. Work through them later in waves.

The result of this step is the send-ready shortlist: a list with name, company, validated email, last touchpoint and the reason this contact is up in this wave.

Selection ends here; the finer split into segments with their own messaging (former customer vs. lost deal vs. old lead, by value, by industry) is its own topic: the article on segmentation will appear here in the guide shortly.

What the shortlist is worth

With the shortlist alone you can already run the numbers: relevant contacts × expected reactivation rate × average order value. Play through your figures in the reactivation calculator before you approve budget for new leads; the reasoning is in How much revenue sits in your CRM?

The next step

The actual campaign starts with the shortlist: define the reason, write the copy, send, follow up. The complete flow is shown in Build a reactivation campaign.

No appetite for cleaning exports and validating lists? With Bestandsgold, a CSV from your CRM is all we need; analysis, enrichment, prioritization and the complete campaign are on us.

Keep reading

Customer reactivation: The complete guide

What customer reactivation is, when it pays off, and how to turn dormant customers, old leads and lost deals into revenue, step by step.

Build a reactivation campaign: The complete process in 9 steps

From CRM data to booked conversations: how to build a reactivation campaign that runs, data, segmentation, reason, copy, sending, follow-up, sales handover and measurement.

Reactivate customers by email: Templates, subject lines, follow-ups

What to write to former customers and old contacts: the anatomy of a reactivation email, subject lines that get opened, the follow-up sequence and the most common mistakes, with templates.