If you want to send files larger than the browser allows, you must enable sending files with the Java Upload Manager. On the General Configuration page, you can specify whether to allow users to specify Java applet uploads via the web portals and whether to make Java applet uploads the default setting. With Java applet upload enabled, Mail Express allows for unlimited file transfers up to 25GB on all file upload portals (Drop-Off, Internal, Reply), matching the Outlook Add-in capabilities. (Attachments cannot exceed the limits set individually for each portal.)
To enable Java applet uploads
Launch the Mail Express Server administration interface. (e.g., click Start > Programs > Globalscape > Mail Express > Mail Express Admin or double-click the desktop shortcut).
Log in using the Mail Express Server administrator username and password that you specified during installation of the server.
In the navigation pane, click Portal Settings > General. The General Portal Settings page appears.
Select the Enable Java applet file transfer via web portals check box to allow users to choose whether to upload files using the Java applet.
Select the Set Java applet upload as default if you want Java applet uploads to be the default setting.