Sieve mode provides syntax-based indentation, font-locking support and other handy functions to make editing Sieve scripts easier.
Use ‘M-x sieve-mode’ to switch to this major mode. This command
runs the hook sieve-mode-hook.
Sieve mode is derived from c-mode, and is very similar except
for the syntax of comments. The keymap (sieve-mode-map) is
inherited from c-mode, as are the variables for customizing
indentation. Sieve mode has its own abbrev table
(sieve-mode-abbrev-table) and syntax table
(sieve-mode-syntax-table).
In addition to the editing utility functions, Sieve mode also contains bindings to manage Sieve scripts remotely. See Managing Sieve.