feedmail-fiddle-plex-user-list

feedmail-fiddle-plex-user-list is a variable defined in `feedmail.el'.
Its value is

nil

Documentation:
If non-nil, should be a list of one or more fiddle-plexes.
Each element of the list can also be a function which returns a
fiddle-plex.

feedmail will use this list of fiddle-plexes to manipulate user-specified
message header fields. It does this after it has completed all normal
message header field manipulation and before calling `feedmail-last-chance-hook'.

For an explanation of fiddle-plexes, see the documentation for the
variable `feedmail-fiddle-plex-blurb'. In contrast to some other fiddle-plex
manipulation functions, in this context, it makes no sense to have an element
which is nil, t, or a simple string.

You can customize this variable.