The Courier mail transfer agent (MTA) is an integrated mail/groupware server based on open commodity protocols, such as ESMTP, IMAP, POP3, LDAP, TLS, and HTTP. Courier provides ESMTP, IMAP, POP3, webmail, and mailing list services within a single, consistent, framework.

virtualenvwrapper is a set of extensions to Ian Bicking's virtualenv tool. The extensions include wrappers for creating and deleting virtual environments and otherwise managing your development workflow, making it easier to work on more than one project at a time without introducing conflicts in their dependencies.

OSmesa is a Mesa extension that allows programs to render to an off-screen buffer using the OpenGL API without having to create a rendering context on an X Server. It uses a pure software renderer.

This transitional package is safe to remove.

Caja is the official file manager for the MATE desktop. This package adds extended functionality to the Caja file manager.

GNU libsigsegv is a library that allows handling page faults in a portable way. It is used e.g. for generational garbage collectors and stack overflow handlers.