### auth/30_exim4-config_examples
plain:
  driver = plaintext
  public_name = PLAIN
  client_send = "${if !eq{$tls_cipher}{}{\
             ^${extract{1}{::}\
               {${lookup{$host}lsearch*{CONFDIR/passwd.client}{$value}fail}}}\
             ^${extract{2}{::}\
               {${lookup{$host}lsearch*{CONFDIR/passwd.client}{$value}fail}}}\
           }fail}"

login:
  driver = plaintext
  public_name = LOGIN
  client_send = "${if !eq{$tls_cipher}{}{}fail}\
                 : ${extract{1}{::}\
                {${lookup{$host}lsearch*{CONFDIR/passwd.client}{$value}fail}}} \
                 : ${extract{2}{::}\
             {${lookup{$host}lsearch*{CONFDIR/passwd.client}{$value}fail}}}"

### transport/30_exim4-config_remote_smtp
remote_smtp:
  debug_print = "T: remote_smtp for [EMAIL PROTECTED]"
  driver = smtp
  hosts_try_auth = DCsmarthost

### CONFDIR/passwd.client
smtp.1und1.com:m12345678-9:beispielpasswort

http://www.mail-archive.com/debian-user-german@lists.debian.org/msg67453.html