Horde Webmail

Log in to Webmail from Client Area, using a direct link, or from cPanel.
Under Change your webmail client click the Horde button.

Click the Open button under the Horde logo.
You can check the checkbox (next to the Open button) Open my inbox when I log in.
From then on, you will see the inbox of your default email account when logging into webmail.

Use the left sidebar to do mail management tasks, such as composing, reading, and sorting messages.
Inbox – displays your current email messages.
Folder Actions – lets you create folders and organize your emails into different folders.
For more read: https://www.horde.org/apps/webmail.

Use the top menu bar to access other features, such as the calendar, address book, tasks, and notes.
Mail – set email filtering rules, compose an email using the New Message editor, and search for an email in any folder.
Address Book – stores the email addresses of your contacts and shares your contacts with your other domain email user account(s).
Calendar – add events into the built-in calendar tool.
Notes – create memos and notes.
Tasks – create and manage a task list.
Bookmarks – add bookmarks from your web browser.
Settings – customize your Horde webmail interface.
For more read: https://www.horde.org/apps/webmail.