SendLater - Email scheduler for Mac Mail.

Customer.io - We make it easy to send emails triggered by user behavior. Build, measure and improve your emails to activate and retain users

Shortwave - Email smarter & faster with a reinvented experience for your Gmail

HubSpot - Grow Better With HubSpot: Software that's powerful, not overpowering. Seamlessly connect your data, teams, and customers on one CRM platform that grows with your business.

Assistant.to - GoToMeeting. Put your GoToMeeting link in the Assistant. to "Location" field. Once the recipient selects a time, you will both receive an invite with a unique GoToMeeting link.

If No Reply - Simple email automation that works for Gmail