Gmail Mail Merge - Send personalized emails with attachments
Mailo - Mailo is an email client where you can send and receive emails to and from anyone with an email address.
Inbox Grader by Freshworks - Free metrics 📈 for your business and team email ✉️
HEY - Email at its best, new from Basecamp.
Dynamic Campaigns by Sigstr - Share the most relevant content in every email
Horde - Horde Groupware is a free, enterprise ready, browser based collaboration suite.