Max Mailboxes for VM Blasting

We are using the VoiceMail Blasting module and are having a problem where VM blasting does not seem to copy the message into all of the mailboxes.

Looking at the logs it appears to stop after 85 mailboxes. We have 3 digit extensions, and 3x85 is 255, so I am curious if we are hitting some kind of character limit someplace (possibly in asterisk or app_voicemail).

Anyone else have any similar experiences with this?