Apps with 'MIME' feature

eM Client is a full featured e-mail client with a modern and easy to use interface. eM Client also offers calendar, tasks, contacts, notes and chat.

Default Programs Editor is a powerful but simple file association utility for Windows 7, Vista and XP. This free utility has three main functions: context menu editor, auto-play editor, and default programs association editor.

FileTypesMan is an alternative to the File Types tab in the Folder Options of Windows. It displays the list of all file extensions and types registered on your computer.

NewsBin Pro is a Usenet NNTP newsreader that downloads and decodes binary file attachments to Usenet posts.

CMail is a command line e-mail sending tool. It was originally developed to assist with testing mail server and content analysis software. As a result, CMail provides many more message formatting and SMTP session control options than similar software.

Replacement for RCDefaultApp, written for macOS Sierra, in Swift 3.

RCDefaultApp is a Mac OS X 10.2 or higher preference pane that allows a user to set the default application used for various URL schemes, file extensions, file types, MIME types, and Uniform Type Identifiers (or UTIs; MacOS 10.4 only).

Lightweight Linux/BSD File Manager.