According to Zendesk support, there isn't a way to tag Offline Message tickets generated from attempted Chat customers. In particular, I'd like to tag these Offline Message tickets with the Chat department they were intended to land in, but were converted to an Offline Message ticket due to all agents within the particular Chat department were offline.

Essentially I'd like to be able to tag these Offline Message tickets by the Zendesk Chat department they were intended to route to, so that I can then set up a trigger within Zendesk Support to look for those particular tags and route these Offline Message tickets to the corresponding email queue (View).