If the variable gnus-use-generic-path is nil, the NNTP
server name followed by the user login name is used in the `Path:'
field of article headers you post. If it is a string, the string
followed by the user login name is used instead. Otherwise, if it is
non-nil, only the user login name is used. This is called the
GENERICPATH feature in the Bnews system.
For example, to define the generic path `flab', put the following codes in `.emacs', `site-init.el' or `default.el'. If you are a system administrator and are installing GNUS for other users, `site-init.el' is the best place to define it because the definition is common to all users of the system having the same domain and organization (see section Domain and Organization).
(setq gnus-use-generic-path "flab")
In this case, the `Path:' field will be generated as `Path: flab!user'.