There is no bulk delete on the server side, in fact you cannot delete messages as an admin. What you can do is setup either single inbox integration or IMAP connection for the user and delete the messages in outlook or login to inbox web portal and delete the messages there, though the web inbox allows only one by one deletion as well.
Just to add a note to the good thoughts from my buddy Chris here (+5 "C")
I would use the "reset" option available with this great tool from the Unity Tools suite. It's called Bulk User Delete but has many reset options as well
Unity Connection Bulk User Delete
For resetting users you have the option of emptying the mailbox, resetting greetings, deleting voice names, resetting passwords, removing private lists and a number of other options you may choose. For installations where the user base “changes over” frequently such as schools this may be a nicer option. This option is also allowed for CoRes installations since it does not involve the removal of user objects from the Connection database.
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The short answer is that you don't.... That isn't entirely true while at
the same time it kind of is, but for the most part you don't configure
the softkeys. You enable or disable them via TCL. Here is the long
answer. Be sure to read the whole thing or e...
Topology: IP Phone > Switches > Microsoft NPS setup to forward 802.1x
proxy to > ISE 2.1 patch 3 Authentication: EAP-TLS using Cisco MIC SANs
Phone Models 802.1X support? 802.1x flavor Addtl Comment EAP-MD5 EAP-TLS
Cisco 3905 Y Y N Cisco 6911 Y Y N Cisco ...