NN uses its news-header and mail-header variables to set headers for
news and mail messages you send.  For example, to set your
Organization header, put the following lines in your ~/.nn/init file:

set news-header Organization: Your Organization Name
set mail-header Organization: Your Organization Name


While reading messages with NN you can view the Organization line
by adding O (the letter "oh") to your header-lines variable setting.
I like the following setting:

set header-lines AFOnWK*Y