sendmail uses ldapmapper to lookup scalix address, which in turn hits against the scalix ldap server (slapd). By default it does an anonymous bind, which won't work once you restrict the aci. Here's how to get ldapmapper to authenticate with credentials:
create ~/s/sys/ldapmapper.cfg with the following:
DN=CN=sxadmin
PASSWD=letmein
If you'd rather, create a ldaplookup account, give it a password, and give it access to your pdl. Then you can use that instead of an admin account. In the end, just make sure sendmail -bv
pdladdress@domain.com works.
After creating that file restart ldapmapper:
service ldapmapper restart
Also, if the scalix ldap server gets pissy restart it with:
omoff -d0 ldap
<wait>
omon ldap