How can I find a custom B2B contact list provider?

There isn't one. You can find a list, but it's guaranteed to be overpriced and the contacts will be outdated. Email lists have a shelf life, but unlike milk or bread, their vendors never rotate the stock. This means regardless of their quoted acceptance rate, you'll overpay for an outdated list. Your best solution is to source your own list, particularly in this niche market, through strategic and targeted lead generation campaigns. Save yourself the wild goose chase of chasing something that doesn't exist. I've purchased lists in niche markets, was quoted high acceptance rates, but after testing the emails against an email validation service such as BriteVerify, found the deliverability rates to be less than half of what I was promised. After running into this same problem more than once, I've developed various lead generation tactics to quickly identify and qualify high quality leads and I'm happy to discuss these with you.

I recommend checking out Netprospex from Dun & Bradstreet. It is was I use and I found it to be reliable. You should know it is expensive. Data.com from Salesforce is Ok too. If it's in your budget, check out what kind of information they have and see if it meets your needs. If you can't find a service that collects the information you need, then you have to collect it on your own. This will be more expensive and time consuming. You will have to create a network of sites that host content that your potential audience would be willing to trade their information for.

I've removed this answer, because I really wasn't answering the question directly.

I agree with David. Purchased records typically are poor quality, old and full of spam traps so it's not recommended to send email campaigns to these records through your own email account as it can have a negative effect on your deliverability, and therefore put any other campaigns you have running at risk.

Plus there is always the question of exactly what permissions these people gave when handing over their email address. You'd want to be absolutely sure the appropriate permissions are in place - if not then your brand could be put at risk.

There are companies who will allow you to buy advertising space in their email campaigns, that might be a better route if you don't have your own list yet but it's always best to start collecting email addresses yourself as soon as possible. Organic data will outperform purchased data every time.

Hi,

Are you trying to use the emails for outbound sales and cold emails trying to start a conversation or is this for marketing efforts?

If you type in that search term in Google you will get a bunch of agencies claiming they build custom lists.

But the real question is how can you be sure they really do?

Here are some signs to look for:
1. Feel of the website - does it look professional or it's a simple page with no contact information or indication of real people. Read their blog, does it sound like they know their stuff?
2. Case studies - do they have real clients, not just fake names. Search the people who gave testimonials on Linkedin and ask if that's true. Don't be lazy!
3. Check their social media profiles, is it a real agency or just some guy with a scraping bot.
4. Get on a short call with them and see if it's a fit.

The best way to make sure you are getting a high-quality service is to ask for a test sample. At least that is how we at Market Republic onboard new clients. If you want to find out more just google us with prospect list building combined.