Step 1: Use the Chrome extension from https://growthers.io/ to export Facebook Group members and their company name.
Step 2: Find the company domain using Toofr or Hunter.io’s domain discovery tool. You may also use Blockspring’s Google Sheet Add-On with Bing Web Search API.
2.Get Email Domains Using Blockspring & Bing Web Search API:
1.Register for Blockspring Google Sheet Add-On (15$/month, or 14 day trial)
2.Get Bing Web Search API key (1,000 calls / month for $3.65)
3.Connect Bing Web Search API key with Block Spring account under Secrets & Tokens:
4.Open the Google Sheet : https://docs.google.com/spreadsheets/d/1q0gSTmfNnLkbBdDhr4ftZ3gCe1L-Eu79ZbD1xN-6kYE/copy
5.Open Blockspring -> Add-Ons -> Blockspring
6.Follow instructions in the Google Sheet. Bing might bug and say you’re out of queries, while you still have, then just try again. It also seems like they are replacing their API system for a new one 31/3/2017.
Step 3: Once you have the domains, then process the data to find their emails using the FindThatLead, Clearbit, or Hunter.io Google Sheet Add-On.
All the add-ons look relatively the same. My preference of choice is FindThatLead based on its competitive pricing and email deliverability rate: