When I choose a different language in the Webaccess, the language is still in English.

When a new user is added to the server, the standard folders are created in the language of the server. When you want to change the standard folders for a user to a different language, you have to change the /etc/zarafa/userscript/createuser script. This has to be done before the user is created in the Zarafa database.
If you want to change the standard folders to, for example, Dutch (nl_NL) you can add the following line to the createuser script:

export LC_MESSAGE=nl_NL.utf8

or replace ‘zarafa-admin --create-store "${ZARAFA_USER}"’ with:

zarafa-admin --lang nl_NL.utf8 --create-store "${ZARAFA_USER}"

When you are using Debian, you have to install the locales before you change the createuser file:

dpkg-reconfigure locales

When the standard folders of an existing user are in the wrong language, they can be changed with Outlook (XP/2003 or higher) to the correct language. It is important that the language of Outlook is the same as the language that you want for your standard folders.

* Close Outlook
* Click on Start > Run
* Type here: Outlook.exe /resetfoldernames

Outlook will start with the standard folders in the same language as Outlook. From now on the standard folders will be in this language.