Mailplane
Used by 12 peoplemailplaneapp.com ↗

“I like MailPlane to open and close email easily while keeping the native Gmail experience.”
Nathan Peretic Interview, Co-founder, Cotton Bureau · via Uses This 
“Mailplane to have a tabbed in-dock closable Gmail app.”
Chris Coyier Interview, Developer (CodePen, CSS-Tricks) · via Uses This 
“I like Mailplane for mail, because it handles multiple accounts well and has lovely keyboard shortcuts.”
Tom Armitage Interview, Game designer, technologist (Hide and Seek) · via Uses This 
“Mailplane makes it easy to switch between these accounts and keeps my email separate from the rest of my browsing, just the way I like it.”
Tom Preston-Werner Interview, Co-founder of Github · via Uses This