Richard,

In the MRS\App_Data\Translations folder is located all of the translation files that SmarterMail uses.  SmarterMail will search this folder for the languages files and then populate the dropdown list accordingly.  If there are language files that you do not want to appear, you can simply remove the corresponding json file.

Thanks Clear! 

Just one question, are those languages added again with a new update?

And I am trying to look up the abbreviations of tje json files, but you probably do not use the ISO abbreviations.

Like cestina is czechoslovakia language and has ISO code cz and not cs

and what is da.json? It looks Danish but Danish abbr. is DK

We do use the ISO 639-1 standard language codes.  On updating, the missing language files would be restored, however, you could make a script that would remove the unwanted language files after the update.

thanks.. learned something. 639 is iso norm languages

I was used to iso 3166, but that's for countries. there are way more languages then countries of course.

Here's a nice reference that lists the language codes cross referenced with the country codes: