1.    Access the web interface as the administrator via the URL: mail.yourdomainname.com using the administrator username and password 


  Note:

  The email account must have administrator privileges to modify the email

  account's disk space in Smartermail 



2.   Navigate to the last button on the top panel > Domain Settings





3.    Select the Accounts from the left panel 




4.    Click on the email account from the email account list.



5.    Modify the Mailbox Size Limit (MB) and save the changes.