1) Access the web interface as an administrator via the URL: mail.yourdomainname.com using the administrator username and password.
Note:
The email account must have administrator privileges to reset the password of the email account through their Smartermail.
2) Navigate to the last button on the top panel > Domain Settings.
3) Select Accounts from the left panel.
4) Click on the email account from the list, then click on the ... button and select Change Password.
5) Enter the new password and click Save.