This function allows you to back up your messages, then import them into your another accounts. Messages are exported in the *.eml file.
1. Open the Export Message form via either of 3 ways.
i. Right-click the message that you want to export, then select Export from the drop-down menu;
ii. Or, tick the checkbox corresponding to the message, then click More Actions on the action bar and select Export from the drop-down menu;
iii. Open the message, then click 
at the upper right corner of the message content and select Export (*.eml) from the drop-down menu.
The Export Message form will appear.
2. Change the file name in the File Name field if needed, and select the export format. At present, only the *.eml format is supported.
3. Click Export to accept exporting your selected message.