The standard Lotus Notes install omits the Australian (and depending on the install options selected, UK) English dictionaries.

Should your Notes client not have access to these files

aus.dic
uk.dic

You can download them here.



Once downloaded, extract the files to your \Lotus\Notes program directory (the same place where notes.exe is located) and then choose the appropriate dictionary file in your Notes user preferences (File -> Preferences -> User Preferences and then the "International" tab).