mh-letter-complete-function

mh-letter-complete-function is a variable defined in `mh-e.el'.
Its value is

ispell-complete-word

• This variable may be risky if used as a file-local variable.

Documentation:
*Function to call when completing outside of address or folder fields.

In the body of the message,
C-M-i runs this function,
which is set to "ispell-complete-word" by default.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 7.1 of the MH-E package that is part of Emacs 22.1.