Neomutt

NeoMutt is a text-based application which interacts with users through different menus which are mostly line-/entry-based or page-based. A line-based menu is the so-called “index” menu (listing all messages of the currently opened folder) or the “alias” menu (allowing you to select recipients from a list). Examples for page-based menus are the “pager”(showing one message at a time) or the “help” menu listing all available key bindings.

The user interface consists of a context sensitive help line at the top, the menu’s contents followed by a context sensitive status line and finally the command line. The command line is used to display informational and error messages as well as for prompts and for entering interactive commands.

NeoMutt is configured through variables which, if the user wants to permanently use a non-default value, are written to configuration files. NeoMutt supports a rich config file syntax to make even complex configuration files readable and commentable.

Because NeoMutt allows for customizing almost all key bindings, there are so-called “functions” which can be executed manually (using the command line) or in macros. Macros allow the user to bind a sequence of commands to a single key or a short key sequence instead of repeating a sequence of actions over and over.
— NeoMutt Manual

Show key bindings
?