Mailbox over quota when quota set to unlimited

Extension mailbox quotas can be set up in advanced profile settings of an extension. If this is blank (indicating unlimited mailbox size) and an extension is still reporting reaching the mailbox quota:

1. Navigate to Setup>Extensions>Groups

2. Modify a group the extension is a member of

3. Delete any entry in the Voicemail/Fax Mailbox quota in order to make the size unlimited