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
Pingdom - With website monitoring from Pingdom you will be the first to know when your website is down. No installation required. 30-day free trial.
Clean Email - Clean Email is an online service that empowers you to take control of your mailbox.
StatusCake - Website Uptime Monitoring & Alerts – Free Unlimited Downtime Monitoring
MailClark - The Slack bot for external communications
Better Uptime - We call you when your website goes down