Hi,
Just adding to KKoeper's point:
There are two ways, you can get voicemail as an email into your inbox.
1. There is an SMTP Forward, i.e. the voicemail is literally forwarded as an attachment to your inbox and both copies are two instances of the same voicemail
2. There is a Unified Messaging where Unity Connection synchs voicemails with the Exchange Server and both servers keep track of the copies and if one instance is deleted or read, then the second instance is also deleted / marked as read.
Either case, I think you can simply add the voicemail sender email address into the Junk Folder and next time onwards Outlook should automatically do it, worst case scenario you can create an Outlook Rule.
HTH
