Backup Mailboxes Only -- not 3rd Party/Aggregated accounts

[jfone]

We are currently backing up with the zimbra backup utility zmbackup.

Unfortunately they are taking too long and using too much storage. A large portion of the mail accounts have aggregated accounts (ie.gmail,yahoo. etc)

I was wondering (hoping) there is a hidden flag or some way to only backup the local accounts but not aggregated accounts.