Hi,
One Idea could be,
You may tweak the "Column List" by clicking the "+" symbol on top right hand side under Network-wide->Clients. [Screenshot attached for reference]
![List Manufacturer.PNG List Manufacturer.PNG](https://community.meraki.com/t5/image/serverpage/image-id/7592i1A7D8AAC614D58AD/image-size/large?v=v2&px=999)
Thereafter you may download the list as CSV file. Filter the content in an Excel Sheet as desired. Copy the List of MAC Address you need to block and Apply "Blocked" Policy for them.
[Screenshot attached for reference]
![Block Policy.PNG Block Policy.PNG](https://community.meraki.com/t5/image/serverpage/image-id/7594i1D42D5079BE85023/image-size/large?v=v2&px=999)
You may also block devices automatically by assigning a "Blocked" group policy on the basis of "Device type" under Wireless->Access Control. [I am not sure if this what you want though]
[Screenshot attached for reference]
![Block Device Type Automatically.PNG Block Device Type Automatically.PNG](https://community.meraki.com/t5/image/serverpage/image-id/7593i1105F84AB172EE76/image-size/large?v=v2&px=999)
I do not see an option of alerting the blocked devices. However you may display a custom blocked message under Network-wide->General for the Blocked Devices.
[Screenshot attached for reference]
![Blocked Message.PNG Blocked Message.PNG](https://community.meraki.com/t5/image/serverpage/image-id/7595i84EA967D7B17C06D/image-size/large?v=v2&px=999)
Regards,
Ajit
AjitsNW@gmail.com
www.ajit.network