[Exim] smtp authentication without pam

I'm trying to make exim auth all incoming mail on unixware 7.1.1

but unixware has no pam.
so I guess exim must search user's passwd from /etc/shadow.

can you give me some hint to set up for authenticatiors.
I set like following... but it doesn't work well...

plain:
driver = plaintext
public_name = PLAIN
server_condition = ${if eq{$3} \
{${lookup{$2}lsearch{/etc/shadow}}}{1}{0}}
server_set_id = $2

and one more question.
what is difference between plain and login.

plain:
driver = plaintext
public_name = PLAIN
server_condition = ${if eq{$3}{${lookup{$2}lsearch{/etc/shadow}}}{1}{0}}
server_set_id = $2

login:
    driver = plaintext
    public_name = LOGIN
    server_prompts = Username:: : Password::
    server_condition =  ${if and {{!eq{$1}{}}{!eq{$2}{}}
{crypteq{$2}{${extract{1}{:}
{${lookup{$1}lsearch{/etc/shadow}{$value}{*:*}}}}}}}{1}{0}}
    server_set_id = $1