Authenticate Postfix through Dovecot with slightly different LDAP settings

[Jakob Lenfers]

Hi,

I'm setting up a server with Dovecot (2.2.2) and Postfix (3.1.0).
Dovecot authenticates against LDAP and Postfix uses Dovecots SASL. That
already works fine. But I would like to have slightly different LDAP
settings for Dovecot and Postfix. Current setup:

passdb {
  driver = ldap
  args = /etc/dovecot/dovecot-ldap.conf.ext
}
userdb {
  driver = ldap
  args = /etc/dovecot/dovecot-ldap.conf.ext
}

Excerpt from dovecot-ldap.conf.ext:

user_filter = (& \
    (objectClass=gosaMailAccount) \
    (allowedServices=*I*) \
    (uid=%u) \
)

I wanted to have sparate LDAP filters (allowedServices=*I* for Dovecot
and allowedServices=*S* for Postfix), to be able to disable SMTP and
IMAP independently. Does anybody know a way to separate those settings?

Thanks in advance,
Jakob