If you ever receive a bounced email or a notification about “Disk Quota Exceeded” you will need to change the mailbox quota for the email account in question, since you received the notification because the mailbox is currently full.
To do this, you must access the VestaCP control panel and click the Mail (1) tab and then Listar cuentas (2) for the domain you want to modify:
Once inside, select the email account you want to modify. In the section labeled Buzón select the desired mailbox size or choose the default size set for the domain. Select Aceptar and the changes will be applied. It's that easy! 🙂