HelpScout - Help Scout is a simple, straightforward way to provide excellent support
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
Intercom - Intercom is a customer relationship management and messaging tool for web businesses. Build relationships with users to create loyal customers.
Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.
HelpNinja - Simple & Affordable help desk
MailClark - The Slack bot for external communications