finger-X.500-host-regexps

finger-X.500-host-regexps is a variable defined in `net-utils.el'.
Its value is

nil

Documentation:
A list of regular expressions matching host names.
If a host name passed to `finger' matches one of these regular
expressions, it is assumed to be a host that doesn't accept
queries of the form USER@HOST, and wants a query containing USER only.

You can customize this variable.

This variable was introduced, or its default value was changed, in version 21.1 of Emacs.