How to reactivate your web agency's old clients with a new service (email template)
If your agency lives off building websites, you have an asset you're probably not exploiting: the list of every client you delivered a project to and never heard from again. Fifty, a hundred, two hundred companies that already paid you, already trusted you and already have your work in production. That dormant roster is worth more than any acquisition campaign — it just needs a reason to wake up.
The classic problem of the design and development studio is that the project model gives no reasons: you deliver, you get paid, and the relationship dies for lack of an excuse to write. "How's everything going?" isn't an email; it's noise. What reopens a business relationship is a piece of news about the recipient's business that they don't know about.
And right now there is one, and it's enormous: most of the websites you delivered don't show up when someone asks an AI. When we measured it with 9,865 Spanish SMEs across 30 sectors, 91% only appeared in 1 of the 4 main AIs (the study, here). Meanwhile, frequent ChatGPT use in Spain has gone from 4% to 28% in two years (Funcas, III AI Survey, 2026). The website you built in 2024 is ready for Google; nobody prepared it for ChatGPT, because ChatGPT barely existed as a channel when you delivered it.
That's your reason to write. Let's get to the full system: preparation, email, follow-up and conversion to retainer.
Step 1: pick 10 and prepare the ammunition
Don't write to the whole list. Pick ten old clients who meet two of three: good mutual memory of the project, a sector where people ask for recommendations (health, renovations, legal, hospitality, professional services), and a business that's still active and growing.
For each one, twenty minutes of prep: think up 3-4 questions their potential customer would ask an AI ("best physiotherapy clinic in Murcia", "trustworthy full-refurbishment company in Valladolid"), try them in ChatGPT, Gemini and Perplexity, and save dated screenshots. They almost certainly won't come up — and if a competitor of theirs does, you've got the best email of the quarter.
Step 2: the reactivation email
From your usual account, in the tone of someone picking up a relationship, not launching a campaign:
Key data
Subject: The website we built you in [2024] and what ChatGPT says about [their company]
Hi [name],
It's [your name], from [your agency] — we built your website in [2024]. I'm writing because this week I've been running a check with former clients and something came up about [their company] that I think you should see.
More and more people are asking ChatGPT and other AIs directly instead of searching on Google: in Spain, frequent ChatGPT use has gone from 4% to 28% in two years (Funcas data). So I tried what a customer of yours would ask, for example: "[real prompt you tried]".
The result: [you don't appear in any of the three AIs I checked / [competitor] appears and you don't / you appear, but with the wrong data]. Screenshots attached.
To be clear: it's not a problem with the website — the website does its job in Google. It's that a new channel has appeared that almost nobody in your sector is working on yet, and that's exactly why whoever moves first starts with an advantage.
If you're interested, I'll show you on a 20-minute call: what I found, what can be done and what it would cost. And if you'd rather do nothing, at least you walk away with the screenshots and know where you stand.
All the best, [your name]
Why it works: the subject line connects the shared past (the website) with the new piece of news (ChatGPT). The line "it's not a problem with the website" is essential — it protects your earlier work and makes clear you're not admitting a fault, but bringing an opportunity. And the close gives value even if they don't buy, which is how you reopen a relationship without pressure.
Step 3: the follow-up (where it really closes)
Half the replies come on the second touch, not the first. After 5-7 days, no reproaches:
Key data
Hi [name], forwarding this in case it got buried. The only thing I'll add: I tried the question "[prompt]" again this week and [you still don't appear / now another competitor appears too]. If you want, let's look at it for 20 minutes this week or next. If it's not the moment, just tell me and I won't push.
If there's still no reply, a third and final touch at 3-4 weeks with a change of angle: a sector update ("I noticed [competitor] has started showing up in Perplexity's answers") or the honest close ("last email about this, promise: I'll keep the report in case it fits one day"). Three touches and that's it; what doesn't close today gets reactivated in six months with fresh data, and that second round converts surprisingly well because by then the problem has grown.
Step 4: from call to retainer
The call follows the script of any sale with a prior audit — show screenshots, explain the why, propose a plan — and you've got the detail of the flow in the audit as a sales hook. But for a project agency there's a strategic nuance: don't sell another project. Sell the monthly fee.
The temptation is to package it as "AI optimisation of your website" for a one-off price, because that's the format your agency knows how to sell. Mistake: AI answers change every week, so the value is in the ongoing watching and work — and that's a retainer of €250-900/month depending on the client's size, with audit, weekly monitoring, fixes, content and a monthly report. For a local business, the three standard packages with deliverables and prices are in how much to charge for managing a local business's AI presence. Ten old clients converted at an average of €400/month is €4,000 of recurring revenue your project agency didn't have — the full shift in model we cover in the monthly service that comes after delivering the website.
The piece that doesn't scale by hand is the checking: testing dozens of questions across several AIs, every week, for each client. That's what we built Surfeo for agencies for: each client in their own space with their prompts monitored weekly across the 4 AIs, PDF reports for your reporting and 3 pitch spaces to audit old clients before writing to them — the email goes out with real screenshots without you losing the afternoon making them.
Frequently asked questions
What if the client replies that the website "no longer works for them" and it's my fault?
Calm and data: the website ranks in Google the same as ever (show it if you can); what's changed is where people ask. In fact, this conversation positions you as the provider who warns of changes before they hurt — which is exactly the opposite of a negligent provider.
Does it work if I built the website 4 or 5 years ago?
Yes, even better: a higher chance of outdated data in the sources (hours, services, addresses) and more genuine urgency. Only the tone of the email changes: "I know it's been a while" in the first line, and the rest the same.
Don't I come across as an opportunistic salesperson writing out of the blue?
You would if you wrote with a generic "we have a new service". You don't if you arrive with screenshots of THEIR business and give away the diagnosis with no strings. The difference between selling and warning is who the protagonist of the email is — and here it's them.
I'm a small agency, how many of the 10 will reply?
With a personalised email and a real screenshot, expecting 3-5 replies and 1-2 closes from the first batch is realistic. It doesn't sound epic until you do the maths: 2 retainers at €400/month is €9,600 a year for a few hours of work on a list you already had.
You already have the list of old clients; what's missing is the ammunition. Take the free visibility test with the websites of your three best former clients and you'll have the screenshots for the first three emails of the week.
