Ranked in these QuestionsQuestion Ranking
Pro Supports many plugins
Functionality and features can be extended by using plugins.
Pro Easy to use
Mailplane 3 looks just like Gmail's web UI and even imports Gmail shortcuts. If Gmail shortcuts aren't ideal for the user, those of Mac can be used instead.
Pro Doubles as a calendar
Mailplane 3 combines Google Calendar and Gmail within a single app.
Pro Can work with mutiple Gmail accounts simultaneously
The tabbed interface included in Mailplane 3 lets users work with as many Gmail accounts simultaneously as they want.
Con Gmail only
Mailplane 3 is a Gmail-only client. It does not support other email providers.