Easymail

Easymail is an Android email client that shows your existing mailbox as chat conversations. Each thread becomes a single conversation with one bubble per message. Quoted text and signatures are folded away automatically, and the reply bar sits at the bottom of the screen, as in a messaging app. Replies quote the original message, so the people you write to receive a normal email.

It works with Gmail, Outlook and Hotmail, iCloud and most other email providers, and keeps several mailboxes in one app without mixing them. Other features: contact groups with To, Cc and Bcc set once, a conversation info page with participants, dates and every attachment, archive with a swipe, filters that search the whole mailbox, a dark theme, five text sizes and a two-pane layout on tablets.

Easymail has no server of its own: the app connects directly to the mail provider over an encrypted connection, and the copy on the phone is deleted when you sign out. It is free, with a single banner ad.