postfix and sacl_check

Hello, I am testing mail service on a Lion Server, and am curious about a number of log entries I am seeing in mail.log. The server is an OD master, and I have about a dozen OD accounts set up with mail service. Receiving and sending mail to/from these accounts works fine. However, when I send test messages from these accounts to external addresses, I see several log entries indicating that sacl_check for the external address (and substrings of the address) has failed. For example, if I send a test message from one of the server accounts to foo@apple.com, I would see (among other log entries indicating successful processing and delivery), the following in mail.log: Aug 5 16:28:11 testserver postfix/smtpd[59115]: sacl_check: mbr_user_name_to_uuid(foo@apple.com) failed: No such file or directory Aug 5 16:28:11 testserver postfix/smtpd[59115]: sacl_check: mbr_user_name_to_uuid(@apple.com) failed: No such file or directory Aug 5 16:28:11 testserver postfix/cleanup[59121]: sacl_check: mbr_user_name_to_uuid(foo@apple.com) failed: No such file or directory Aug 5 16:28:11 testserver postfix/cleanup[59121]: sacl_check: mbr_user_name_to_uuid(@apple.com) failed: No such file or directory Aug 5 16:28:12 testserver postfix/cleanup[59121]: sacl_check: mbr_user_name_to_uuid(foo@apple.com) failed: No such file or directory Aug 5 16:28:13 testserver postfix/cleanup[59121]: sacl_check: mbr_user_name_to_uuid(@apple.com) failed: No such file or directory Again, delivery is succeeding as expected, but these log entries still concern me. Can anyone shed light? sacl_check in postfix seems to be new to Lion as far as I can tell. I have never seen entries like this in prior versions of OS X Server.