Symptom
Mac OS X 10.2 Mail does not use LDAP when only the first character of an address is entered in the address field. It waits for the second.
Solution
When you enter the first character of an address, Mail will search the local directory only.
If you have configured Mail to use an LDAP server, it searches both the local and remote directory for an address after you enter the second character. All subsequent characters entered into the address field cause Mail to search local and remote directories.
For more information, see technical document 107201, "
Mac OS X 10.2 Mail: Address Auto-Completion Uses 'Most Often Used' Address".