feedmail-before-fcc-hook

feedmail-before-fcc-hook is a variable defined in `feedmail.el'.
Its value is

nil

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

Documentation:
User's last opportunity to modify the message before Fcc action.
It has already had all the header prepping from the standard package.
The next step after running the hook will be to save the message via
Fcc: processing. The hook might be interested in these: (1)
`feedmail-prepped-text-buffer' contains the header and body of the
message, ready to go; (2) `feedmail-address-list' contains a list of
simplified recipients of addressees to whom the message was sent (3)
`feedmail-error-buffer' is an empty buffer intended to soak up errors
for display to the user. If the hook allows interactive activity, the
user should not send more mail while in the hook since some of the
internal buffers will be reused and things will get confused.

You can customize this variable.