Mailmeteor - Send hundreds of personalized emails with Gmail.
MailChimp - MailChimp is the best way to design, send, and share email newsletters.
GMass - GMass allows you to easily schedule emails, send out mass emails and mail merge campaigns and more with Gmail! Click here to learn about more features!
Streak - Manage customers inside Gmail
SmartrMail - SmartrMail is the easiest way to send best practice newsletters and automations for your store
Interseller - Interseller helps find contact information, reach out to them with email automation and syncs it all into your database.