You use multiple directories that are referenced by DA. Name Lookup order is set
In each directory there is an user named "Michael Smith"
In the main names.nsf on the Domino-Server, there is also a user named "Michael Smith"
If you send an e-Mail and type in "Michael Smith", the Clients looks up the name and presents an alphabetically sorted list of all entries named "Michael Smith", but does not honor the Name Lookup Order in the DA, so the in-company "Michael Smith" is not on top of the list, but somewhere in the middle of th list.
Most of the times, users send mails to the in-company "Michael Smith" so this is an annoying behaviour and can also lead to data leakage.
In Notes 8.5.x the lookup listed the in-company "Michael Smith" on top of the list as expected.
Please create an option to either honor the Name Lookup Order in the DA when making name lookups from the Client or at least list the entries from the servers names.nsf on top.