A brilliant postcard sent to the wrong address doesn't convert. It doesn't even arrive. Before creative, offer, or timing, the list is the thing that decides whether a campaign has any chance at all, and it's the part most businesses spend the least time on.
Here's how to build one properly, whether you're starting from your own customer data, buying in new prospects, or both.
Start with what you already have. Your existing customers, past enquirers, and anyone who's given you their details are almost always your best-performing list, because there's already some relationship there. Direct mail has an open rate of up to 90%, significantly higher than email's 20 to 30% (Source: Market Reach), and that advantage is strongest on a list that already knows who you are.
Once your house list is in good shape, expansion usually comes from one of two directions: sourcing new prospect data, or asking existing customers to bring others in. For UK B2B targeting specifically, ProspectFeed gives you a way to reach newly registered businesses using live Companies House data, filtered by industry and location, updated daily. It's a genuinely useful way to reach companies before your competitors do, since the data reflects new registrations rather than an aged, recycled list.
However your customer data currently lives, spreadsheet, CRM export, ecommerce platform, it needs to end up as a clean CSV before it's ready to mail. Stannp.com's dashboard accepts a straightforward CSV upload, so there's no need for special formatting software or a developer to get your first list into the platform.
Knowledgebase article: How do I upload my mailing list?
If your data sits in a CRM or marketing platform already, integrations with the likes of HubSpot, Zapier and Make, or via API mean you can pull data across without manually re-exporting every time you want to run a campaign.
Because a piece of mail sent to a wrong or incomplete address doesn't just fail to convert, it costs you the postage and print for nothing. Stannp.com's built-in address verification checks every record against the Royal Mail Postal Address File (PAF) before it goes to print, catching formatting errors, incomplete addresses, and obvious mistakes before they turn into wasted spend.
This matters more the bigger your list gets. A small error rate on a list of 200 barely registers. The same error rate on a list of 20,000 becomes a genuinely significant amount of wasted postage, and a meaningful dent in your response rate calculation, since undelivered mail can never generate a response.
Both have a place, but they solve different problems. Building from your own data (customers, enquirers, newsletter sign-ups) gives you a warmer audience with a real chance of conversion, but it caps out at the size of your existing relationships.
Bought or sourced third-party data extends your reach to people who've never heard of you, which is valuable for growth but starts from a colder position. This is where a source like ProspectFeed earns its keep for UK B2B. Rather than a generic bought list that's been resold repeatedly, you're targeting businesses that registered recently, which means less list fatigue and a genuinely fresh audience.
A single list sent one generic message is the most common way to underperform. Even basic segmentation, by location, purchase history, or business size, tends to improve results meaningfully, because the message can actually speak to something true about the recipient rather than a lowest common denominator.
For UK B2B campaigns, ProspectFeed's filtering by SIC code (industry classification) and geography means you can build a segmented, targeted list from the outset, rather than segmenting after the fact from a broader pool.
Smaller than you'd think. Stannp.com has no minimum order, so you can send a test batch to a few hundred records, see how the list performs, and only commit to a full send once you've confirmed the data and message are working. This matters especially for a newly sourced list, testing on a small batch first means any data quality issues surface before you've spent a full campaign's budget finding out.
Export or download your customer data as a CSV, upload it through the Stannp.com dashboard, let address verification catch any errors, and send a small test batch before scaling up. If you're targeting new UK business prospects, ProspectFeed lets you build a fresh, filtered list directly inside the platform without sourcing data externally at all.
Ready to build your first list? Create your free Stannp.com account and upload your first CSV, or explore ProspectFeed to start targeting new UK businesses today.
Start with your existing customer or enquirer data. It's your warmest audience and typically your best-performing list. Expand from there using a source like ProspectFeed for new UK business prospects.
Ideally, yes, though Stannp.com's built-in address verification will catch most formatting errors and incomplete addresses automatically once you upload, checking each record against the Royal Mail Postal Address File.
ProspectFeed is a Stannp.com feature that uses live Companies House data to surface newly registered UK businesses, filtered by industry and location. Unlike a generic bought list, the data reflects genuinely recent registrations rather than a recycled or resold file.
As small as you like. Stannp.com has no minimum order, so testing a new list or a new source on a few hundred records before committing to a full campaign is a normal and sensible approach.
Segment where you can. Even basic segmentation by location, industry, or purchase history tends to lift response rates, because the message can be more directly relevant to each group.
Both work. A straightforward CSV upload is the simplest route, but integrations or using the API let you pull data across without manual exporting each time.