Answering myself it may be related to
http://lists.freebsd.org/pipermail/freebsd-ports-bugs/2006-April/086659.html
I'm using openldap-server-2.3.24 and nss_ldap-1.250.
My /var/log/debug.log was full of:
Jul 22 20:34:04 castor sm-mta[58735]: NSSWITCH(nss_method_lookup): ldap,
passwd, endpwent, n
I have two boxes running FreeBSD 6.1-RELEASE.
AFAICS their configuration is identical.
On both machines, I put at the end of /etc/crontab:
14 8 * * * root echo test
On one machine root receives a mail with "test" as the boby
of the message while on the other machine I have no mail.
Here are the