Clearbit - Clearbit provides Business Intelligence APIs
Roundcube - Web-based IMAP email client
ZoomInfo - ZoomInfo is a B2B database providing detailed business information on people and companies.
HEY - Email at its best, new from Basecamp.
InsideView - InsideView aggregates and curates all the company and contact data, news and social insights, and professional connections you need to do business better.
Mailo - Mailo is an email client where you can send and receive emails to and from anyone with an email address.