imap-kerberos4-program

imap-kerberos4-program is a variable defined in `imap.el'.
Its value is

("imtest -m kerberos_v4 -u %l -p %p %s" "imtest -kp %s %p")

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

Documentation:
List of strings containing commands for Kerberos 4 authentication.
%s is replaced with server hostname, %p with port to connect to, and
%l with the value of `imap-default-user'. The program should accept
IMAP commands on stdin and return responses to stdout. Each entry in
the list is tried until a successful connection is made.

You can customize this variable.