Every state publishes who holds a business license. It's public, it's current, and it covers niches that bought lead lists handle badly. The lead database I used returned junk for vets and restoration firms, so I went to the license files instead.
Step 1: Find the license file
Search "[your state] license lookup" plus the trade. Some states publish the whole list as a spreadsheet. Texas publishes its files on the TDLR download page and updates them every day:
https://www.tdlr.texas.gov/LicenseSearch/licfile.asp
Two lists I use: Texas mold remediation companies (456 current) and Florida veterinary establishments (3,134 current).
Step 2: Or search the state portal
Florida's portal is the DBPR license search:
https://www.myfloridalicense.com/wl11.asp
Filter to current licenses, and watch the wording. Florida marks open licenses "Current" or "Current, Active". Filtering on "active" kept only 426 of 3,134 vet practices.
Step 3: Match each license to a real business
Search each license on Google Maps using the full address.
Accept a match only if the phone number matches, or the name mostly matches and the ZIP code is the same.
Drop anything that isn't a business: school districts, cities, and people at home addresses.
Step 4: Find an email, then verify it
Check the business website: the homepage, contact page and about page.
Prefer a named person over info@.
Run every address through a verifier and send only to "safe".
What one batch gave me
Florida vet practices: 600 licenses checked, 365 matched to a real business, 169 had an email, 115 loaded into campaigns. The lookups cost $2.58.
What didn't work
Florida mold remediators: licensed to individuals at home addresses. 0 of 148 matched a business.
Filtering on "active": missed most open licenses. Use "current".
The Texas mold list, unfiltered: includes school districts and cities. Drop them by name.
Pick lists where the license belongs to a business, not a person.