Step 1: Login to the cPanel account that owns the email address you want to Import.
On the main cPanel page, click the Email Accounts button.
On the Email Accounts page, find the email address you’d like to import emails for then click Access Email.
Step 2: You should see a Webmail login page where you’ll need to enter the email address and password to login. Once you’re logged in, you will be presented with a page to choose your Webmail client.
Select Horde when presented. Once Horde is fully loaded you will see an interface similar to the following screenshot.
Step 3: Within Horde, right-click Inbox and select Import from the list.
Step 4: Here you will see a popup to select your MBOX file for uploading. Select the file by clicking Browse to use the file picker.
Simply click OK and Horde will begin the import of your emails. After clicking OK you should return to the main Horde dashboard, where you will begin to see the imported emails to populate. With this step complete, you will see that all your emails were imported.