iLink - iLink enables users to log emails, lookup customers, create new CRM records and run powerful searches all without leaving Gmail.

Freshdesk - Freshdesk is a cloud-based customer support software that lets you support customers through traditional channels like phone and email, social channels like Facebook and Twitter, and your own branded community

MailDrop - maildrop is a Mail delivery agent used by the Courier Mail Server. The maildrop MDA also includes filtering functionality. maildrop receives mail via stdin and delivers in both Maildir and mbox formats.

Salesforce Service Cloud - Service Cloud integrates customer service with social networks and provides a self-service customer portal and knowledge base system.

Sanebox - SaneBox is a cloud-based service that allows users to filter and manage their emails.

Zendesk Support - Social Customer Support and Help Desk and Ticketing