sieve-mode
sieve-mode is an interactive autoloaded Lisp function in `sieve-mode.el
'.
(sieve-mode)
Major mode for editing Sieve code.
This is much like C mode except for the syntax of comments. Its keymap
inherits from C mode's and it has the same variables for customizing
indentation. It has its own abbrev table and its own syntax table.
Turning on Sieve mode runs `sieve-mode-hook'.