Boomerang
8.1#2 in sales email tracking softwareFrom $4.98 a monthFree planAndroidiOSWebAPI
VisitBoomerang suits Gmail users who want to schedule messages, pause incoming mail, and manage follow-ups. Its team scheduling tools may suit organizations coordinating meetings across calendars.
MailTracker suits Gmail users who need open, click and follow-up signals from a Chrome extension. It is also relevant to users who can manage broad Gmail permissions and tracking limitations.