Deprecated since version v2.3.0.
This userdb is probably useless with Dovecot v2.0.12+, since it uses
getpwnam_r(), which supports error reporting.
It can’t distinguish between temporary and permanent errors.
So if you’re using e.g.
nss_ldap and your LDAP database is down, all userdb
lookups may return
user doesn't exist errors. This is especially bad if
you’re using Dovecot LDA, which causes the mails to be bounced back to sender.
The NSS userdb works around this problem by loading the NSS modules and calling them itself. This is a bit kludgy, and it probably works only with Linux.
This userdb has two parameters:
service=<name>: This parameter is required. The name specifies what NSS module to use, for example
blocking=no causes the lookups to be done in auth master processes instead of in worker processes.
driver = nss
args = service=ldap