Notepad++ have a nice word autocomplete feature I think emClient also need.
Autocomplete suggestions are based on words already written in the body.
win10 has a similar function, Word Prediction
And Outlook auto correct is super.
https://www.openoffice.org/sv/download/
And OpenOffice has a superb word predict and autocorrect function i wish emClient implement.
Best I have seen so far.