My use case for SmarterMail is non-typical.  We use it as a strictly receive only system, to power an email ingesting/processing integration.  There are no actual end users, only per-system mailboxes, for hundreds of different domains.   

Since we're only importing emails, there's no need for Calendar support, or for other features like GAL, Feeds, WebDav, LDAP, etc.   Most of those other features can be turned off or ignored without consequence, however when an email comes in that was a forward of a calendar invite, a Calendar entry is created with any attachments.  Since we're handling a lot of emails the additional disk space usage from this happening is significant, even with the minimum 3 month auto clean period enabled.

We'd like the ability to turn off the Calendar at a domain or system-wide level.  Or alternatively this could be a per-user mailbox setting, as long as that that setting could be defaulted.