[exim] SMTP AUTH / saslauthd

Hello,

we have a strange behavior of exim with SMTP AUTH using the authenticator

plain:
driver = plaintext
public_name = PLAIN
server_prompts = :
server_condition = ${if saslauthd {{$2}{$3}} }
server_set_id = $2

results in

3823 Process 3823 is ready for new message
3823 plain authenticator:
3823 $auth1 =
3823 $auth2 = username
3823 $auth3 = password
3823 $1 =
3823 $2 = username
3823 $3 = password
3823 Running saslauthd authentication for user "username"
3823 saslauthd userid='username' servicename='' realm=''
3823 Answer 'NO PAM auth error' received.
3823 saslauthd: access denied (NO PAM auth error)
3823 expanded string:
3823 LOG: MAIN REJECT
3823 plain authenticator failed for mailfrontend-7.intern.tu-berlin.de (test) [172.26.9.235]: 535 Incorrect authentication data (set_id=username)

Username/Password is correct.

# testsaslauthd -u username -p password
0: OK "Success."


Where is the problem located?

The same (?) config works on an other host. If not same where might be the difference?


--Frank Elsner