It is possible to add additional languages to the OXtender/Notifier that are not supported by Open-Xchange.
.po files consist of a msgid and a msgstr and are human-readable. The msgid contains the English source and must not be modified. The msgstr contains the translation of the msgid entry. Best use KBabel under Linux or poEdit under Windows for translating the file.
.mo files are the machine-readable version of the .po file. Use msgfmt to convert the .po file or use poEdit/KBabel. Normally, the .mo files are created automatically.
If there are updates you will get the .pot file with the English strings. To use your already existing translation use msgmerge -o new.po old.po new.pot. Or merge with another tool, like poEdit.
\OXtender installation directory\locale\gg\LC_MESSAGES\