The language a user selects/sets for their account in SmarterMail -- also known as localization or internationalization -- is EXTREMELY important. That's because it's much more than simply what is seen in the webmail client. SmarterMail's language selection is the basis for everything: the things you see in the webmail interface as well as what's returned to an email client when you connect using Outlook, eM Client, iOS Mail and more. That includes things like settings labels, folder names, calendars and calendar appointment, contact groups, email message content, log files and essentially everything within SmarterMail.
Therefore, it is extremely critical that whatever language is set in SmarterMail is the language you actually want to use.
For example, BEFORE importing a PST from Microsoft Outlook, it is essential that the language selection in SmarterMail matches the language of the PST file. If this isn't done, you will have 2 versions of all the folders that are imported: those already in webmail that are in the language set for the user (e.g., Inbox, Sent Items, Deleted Items, default calendars, pre-existing contacts, etc.) PLUS those that are imported from the PST, which could be in a completely different language. You will then have to go through and move items around, delete incorrect folders, fix calendar appointments, etc. This can be a time consuming process and may even lead to missing messages, missing contacts or incorrect calendar appointments.
SmarterMail Language Selection and Protocols
When communicating with a client using EWS, EAS, MAPI, or IMAP, SmarterMail will send the default folder names to the client using the language that the user has saved on the server. Unfortunately, many clients will use their own internally defined folder names for many default folders. Therefore, the folder names in SmarterMail may not match exactly to what's used in the client. In addition, because of the way the IMAP identifies the Inbox, that folder will always show up in the client's configured language and ignore what is sent over from SmarterMail.