- Navigate to Mail Info > Mail Manager.
- Select the domain you wish to increase a mailbox quota for.
- Select the MB link for the mailbox you wish to increase.
- Enter the new size for your mailbox and click the Submit button.
From this moment on, you will be charged for the difference between this new amount and the free amount your hosting plan grants. This charge will be added to the recurrent fee at the beginning of each billing period.
Note: You cannot change quota for the postmaster mailbox.