I'm seeing a constant and never-ending stream of LDAP errors in my zimbra.log. Any suggestions when what to look for or try? I've already followed the tuning for large deployments wiki document and increased the ldap cache sizes to larger than than the size of the .db files and entries cache to greater than the number of accounts.

Sep 24 15:15:59 zcs amavis[5265]: (05265-01-2) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:00 zcs amavis[3590]: (03590-03-11) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:01 zcs amavis[3231]: (03231-03-8) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:01 zcs amavis[3498]: (03498-02-9) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:01 zcs amavis[3453]: (03453-02-7) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:01 zcs amavis[5181]: (05181-01-4) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:02 zcs amavis[3136]: (03136-02-10) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:04 zcs amavis[3468]: (03468-02-9) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:04 zcs amavis[3639]: (03639-03-4) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:04 zcs amavis[3800]: (03800-02-7) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:04 zcs amavis[3335]: (03335-02-9) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:04 zcs amavis[3641]: (03641-03-3) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:04 zcs amavis[3768]: (03768-02-6) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:04 zcs amavis[3471]: (03471-02-8) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 15:16:05 zcs amavis[3820]: (03820-02-4) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR

Here is one of them with log_level at 5.
Sep 24 18:13:50 zcs amavis[10682]: (10682-02) ESMTP< RCPT TO:<figueral@tcnj.edu>\r\n
Sep 24 18:13:50 zcs amavis[10682]: (10682-02) switch_to_my_time 480 s, SMTP RCPT received
Sep 24 18:13:51 zcs amavis[10682]: (10682-02) lookup_acl(figueral@tcnj.edu) matches key ".", result=1
Sep 24 18:13:52 zcs amavis[10682]: (10682-02) lookup (local_domains) => true, "figueral@tcnj.edu" matches, result="1", matching_key="."
Sep 24 18:13:53 zcs amavis[10682]: (10682-02) query_keys: figueral@tcnj.edu, figueral, @tcnj.edu, @.tcnj.edu, @.edu, @.
Sep 24 18:13:53 zcs amavis[10682]: (10682-02) lookup_ldap "figueral@tcnj.edu", query keys: "figueral@tcnj.edu", "figueral", "@tcnj.edu", "@.tcnj.edu", "@.edu", "@.", base: , filter: (&(objectClass=amavisAccount)(mail=%m))
Sep 24 18:13:54 zcs amavis[10682]: (10682-02) ldap begin_work
Sep 24 18:13:55 zcs amavis[10682]: (10682-02) lookup_ldap: searching base="", scope="sub", filter="(&(objectClass=amavisAccount)(|(mail=figue ral@tcnj.edu)(mail=figueral)(mail=@tcnj.edu)(mail= @.tcnj.edu)(mail=@.edu)(mail=@.)))"
Sep 24 18:13:55 zcs amavis[10682]: (10682-02) NOTICE: do_search: trying again: LDAP_OPERATIONS_ERROR
Sep 24 18:13:56 zcs amavis[10682]: (10682-02) disconnecting from LDAP