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
Hiver - Manage Customer Support, Sales and Projects right from your Gmail inbox. Collaborate with Shared Labels, Shared Contacts, email notes, email reminders and email templates
Zoho Desk - Industry's first context-aware Helpdesk Software
Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.
Salesforce Service Cloud - Service Cloud integrates customer service with social networks and provides a self-service customer portal and knowledge base system.
DuoCircle - DuoCircle provides enterprise spam filtering and email management solutions.