feedmail-ask-for-queue-slug

feedmail-ask-for-queue-slug is a variable defined in `feedmail.el'.
Its value is

nil

Documentation:
If non-nil, prompt user for part of the queue file name.
The file will automatically get the FQM suffix and an embedded
sequence number for uniqueness, so don't specify that. feedmail will
get rid of all characters other than alphanumeric and hyphen in the
results. If this variable is nil or if you just hit return in
response to the prompt, feedmail queuing will take care of things
properly. At the prompt, completion is available if you want to see
what filenames are already in use, though, as noted, you will not be
typing a complete file name. You probably don't want to be bothered
with this prompting since feedmail, by default, uses queue file names
based on the subjects of the messages.

You can customize this variable.