Mail Dump - Powerful Extensions for email addresses extracting, verifying and finding
Verifier - Weed out disposable, non-existent domains or invalid emails.
Castle - The easiest way to protect your users from getting hacked
Validator.pizza - Free API to block 🗑 disposable emails
Truecaller - Find a person by a name or phone number worldwide for free using Truecaller.
Antideo - Email, IP address and phone number validation API service