Notes 10 and dictionaries

XTAF dictionaries are available to enable an English client to spell check e.g. in German...

Please consider the post of Daniel Nashed's Blog. I can confirm the troubles on Windows! In a test environment, the installation of the XTAF dictionaries from Notes 9.0.1 did destroyed my Notes 10.0.1 Client.

For MacOS I prefere:

1. In the notes.ini add the following key: "SPELL_FORCE_LEGACY=1" (you can find the notes.ini in: "~/Library/Preferences/Notes Preferences")
2. Download the dictionaries  *.dic and *.aff files, so called Hunspell dictionaries, the same you can use with Open Office.
3. Copy the *.dic and *.aff files to: ~/Library/Spelling
4. Restart Notes 10

Source: https://www-01.ibm.com/support/docview.wss?uid=swg21970094