After upgrading a 7.0.2 Sametime Server to 8.0.2 clients running Notes 6.5 are unable to log in, refusing their password and generating error “Instant messaging error code (0x80000003)”, while newer Notes clients connect fine.

Solution is in technote http://www-01.ibm.com/support/docview.wss?uid=swg21246882

Sametime Server 8.0.2 default settings, for client types which can connect, does not include Notes clients 6.5.x. Adding 1002 to the VPS_ALLOWED_LOGIN_TYPES entry, of the servers Sametime.ini, allows the older client to access the server.