In short: to choose a good B2B database, look at six criteria: where the data comes from and on what legal basis, how up to date it is, how precisely you can segment it by industry, location and company size, which guarantee covers invalid contacts, what the price actually includes, and which platform you will use to send to it. Before buying, always ask for the data source, the date of the last update and the refund terms.
A good B2B database answers six questions well: where the data comes from, how up to date it is, how relevant it is, how reliable it is, what the price includes and which tool you will use it with. As a ConnyLine partner, the platform we chose to get the most out of our databases, here at Bancomail we walk you through the six questions to ask before choosing a B2B database.
When choosing a database, most people start with the number of contacts. It is a useful figure, but it only tells part of the story: what really drives results is the quality and relevance of the records, and how confidently you can work with them after the purchase.
1. Where the data comes from
The first question to ask a supplier is simple: where did you get these contacts? A serious database declares the origin of its data and can document it. It matters in practice too, because anyone who receives a message has the right to know how they were reached.
The EU General Data Protection Regulation (Article 14) requires that data subjects be informed when their data is not collected directly from them. A reliable supplier informs data subjects before passing on their data and helps you do your part: clear guidance on when consent is needed and when you can rely on legitimate interest, depending on the channel (email, phone, post), and a privacy notice template you can use in your outreach.
What to ask for: the data source, the supporting documentation and a sample privacy notice. For specific cases, your privacy consultant's opinion is always the safest step.
2. How up to date it is
A B2B database changes over time, and that is completely normal: companies move, open, close and change their contact details. It is not a supplier flaw, it is the nature of the data.
What sets a good supplier apart is how it manages this cycle. Ask what its approach to updates is: how often it runs them, with which checks, and whether there is a way to renew or top up the database over time, so it stays useful well beyond your first sends.
3. How relevant it is
Ten thousand right contacts are worth more than a hundred thousand generic ones. Check that the database can be segmented with criteria that fit your goal. In a Bancomail database, for example, you can select by industry (over 1,800 micro-categories, also by ATECO code), by location (country, region, province, city, postcode) and by company size (revenue and number of employees, where available), as well as by legal form. Depending on the category, there are also micro-sector filters, such as star ratings for hotels or cuisine type for restaurants. The more precise the target, the more specific your message can be, and the more likely it is to interest the people who receive it.
A simple test: tell the supplier who you would like to write to and see whether they can turn it into a concrete selection, with the number of available contacts shown before you buy.
4. How reliable it is
Even in a well-kept database, a small share of addresses may no longer be deliverable. What matters most is how the supplier takes responsibility for it. Look for a written guarantee with clear terms and timing: what it covers, by when you can report a problem and how replacement works.
On a Bancomail database, for example, the guarantee lasts 60 days from purchase: a reasonable window to run a first send, measure results and report any anomalies.
5. What the price includes
Price matters, but what it includes matters even more. Two databases with the same number of contacts can be worth very different amounts, because what sets them apart is the work behind them. So ask the supplier what the cost covers: data checks, profiling by industry, support and legal oversight of compliance. In a Bancomail database, for example, the price includes 21 verification processes (periodic ones and checks before every delivery), a dedicated profiling team, support in 5 languages with a reply within 24 hours, and an in-house legal team that monitors GDPR compliance.
A database with a lower unit cost can look like a better deal. But if the data is outdated, the emails are unverified or compliance is uncertain, the risk lands on your campaigns: lower deliverability, a damaged sending domain reputation, possible complaints from recipients. To compare suppliers, check whether they offer a transparent refund on invalid emails, the data history from origin to delivery (so you know exactly what you are buying) and support with clear response times.
6. Which tool you will use it with
The last criterion is what happens after the purchase. A database performs best when you can write to the contacts effectively and within the rules.
Many general-purpose email marketing platforms are not optimized for this. They are built for writing to subscribers who have given their consent, so their policies often exclude purchased or third-party profiled lists, and their automatic controls (on bounces and complaints) are tuned to that kind of audience. With cold marketing you can end up with a suspended account right in the middle of a campaign. So check beforehand, not afterwards, that your chosen tool is compatible with cold marketing, meaning it is designed for this type of sending.
It is one of the reasons why, at Bancomail, we decided to partner with ConnyLine: whoever buys a Bancomail database can rely on a platform built to write to new contacts in full compliance and with top performance. How the integration works is explained on the page about the ConnyLine B2B email database.
The Bancomail + ConnyLine promo
To support you throughout the whole journey of choosing a database, from September 22 to October 25, 2026 we have launched a promotion with ConnyLine, with two distinct benefits:
- 30% off the purchase of a Bancomail database
- a ConnyLine Line ONE Special plan included, sized to cover at least one send to the entire database you purchased
How it works:
- You buy the database on the Bancomail website, with the discount already applied.
- Together with the delivery you receive instructions to request activation of the plan.
- You have 60 days from the purchase date to do so.
- ConnyLine contacts you to activate the plan and set up your account.
Once activated, the plan is yours for 3 months. The assigned package is always the one of the next size up, or equal to, the contacts purchased, up to a maximum of 360,000 emails. The plan has no additional costs, except for any extra services you choose to buy on your own (extra sends, sending service, creatives). The 30% discount can be combined with other promotions or reserved discounts, up to a maximum of 50% of the list price, VAT excluded.
See the promo Browse Bancomail databases
Questions to ask before you buy
To have everything at a glance, here are the six questions to take with you to your next conversation with a supplier:
- Where does the data come from, and how can I document it?
- When was it last updated, and how is it kept up to date over time?
- Can I select exactly my target and see how many contacts are available?
- What guarantee is offered, under what conditions and for how long?
- What is included in the price, beyond the number of contacts: checks, profiling, support, compliance?
- Which platform can I use to write to the contacts, within the cold marketing rules?
If you have doubts about any of these points, the Bancomail team is available to help you choose the database that best fits your project.
Article by Bancomail for ConnyLine.