Mailchimp Transactional Email (formerly Mandrill) is a reliable, scalable and secure delivery API for transactional emails from websites and applications.
Gmail is a free, advertising-supported email service offered as part of Google's G Suite, with 15GB of storage, color-coded inbox filters and unsend button.
Zendesk is a cloud-based customer service software solution trusted by over 40,000 organizations worldwide. Companies such as Groupon, Box, and Zappos are using Zendesk to lower costs, raise productivity, and increase customer satisfaction.
Recruitee is Software as a service (Saas) that functions as an applicant tracking system (ATS). It includes a careers site editor for employer branding, a plugin for sourcing (personnel), job board integration, email and calendar synchronization.