feedmail-spray-address-fiddle-plex-list

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

nil

Documentation:
User-supplied specification for a crude form of mailmerge capability.
When spraying is enabled, feedmail composes a list of envelope addresses.
In turn, `feedmail-spray-this-address' is temporarily set to each address
(stripped of any comments and angle brackets) and a function is called which
fiddles message headers according to this variable. See the documentation for
`feedmail-fiddle-plex-blurb', for an overview of fiddle-plex data structures.

May be nil, in which case nothing in particular is done about message
headers for specific addresses.

May be t, in which case a "To:" header is added to the message with
the stripped address as the header contents. The fiddle-plex operator
is 'supplement.

May be a string, in which case the string is assumed to be the name of
a message header field with the stripped address serving as the value.
The fiddle-plex operator is 'supplement.

May be a function, in which case it is called with no arguments and is
expected to return nil, t, a string, another function, or a fiddle-plex.
The result is used recursively. The function may alter the value of the
variable feedmail-spray-this-address, perhaps to embellish it with a
human name. It would be logical in such a case to return as a value a
string naming a message header like "TO" or an appropriately constructed
fiddle-plex. For an example, see feedmail-spray-via-bbdb.

May be a list of any combination of the foregoing and/or
fiddle-plexes. (A value for this variable which consists of a single
fiddle-plex must be nested inside another list to avoid ambiguity.)
If a list, each item is acted on in turn as described above.

For example,

(setq feedmail-spray-address-fiddle-plex-list 'feedmail-spray-via-bbdb)

The idea of the example is that, during spray mode, as each message is
about to be transmitted to an individual address, the function will be
called and will consult `feedmail-spray-this-address' to find the
stripped envelope email address (no comments or angle brackets). The
function should return an embellished form of the address.

The recipe for sending form letters is: (1) create a message with all
addressees on Bcc: headers; (2) tell feedmail to remove Bcc: headers
before sending the message; (3) create a function which will embellish
stripped addresses, if desired; (4) define `feedmail-spray-address-fiddle-plex-list'
appropriately; (5) send the message with `feedmail-enable-spray' set
non-nil; (6) stand back and watch co-workers wonder at how efficient
you are at accomplishing inherently inefficient things.

You can customize this variable.