Email Verification on Google Sheets - An add-on for email verification directly in Google Sheets
Vtenext - Vtenext is a platform that allows you to tackle CRM processes and customers with great ease.
Verifier - Weed out disposable, non-existent domains or invalid emails.
ZEKI CRM - ZEKI CRM is a full-fledged and multi-features solution that enables businesses to fulfill all their needs in a single place.
Clearbit Salesforce Prospector - Quickly build targeted lead lists directly in Salesforce
Teamgate CRM - Powerful CRM without the Salesforce Price tag.