When a ticket is sent to a group via email with no assigned user you can Acknowledge the ticket by replying and adding Response Codes to the subject line such as ACK for acknowledge or CL for closed, etc.... This will change the status.
The question i have, can you perform the same task, ACK the ticket and add an Assignee as well?
eg. Just Acknowledging would be "Incident 453432 Initial". You reply to the same email with "Incident 453432 Initial ACK" and it get's acknowledged.
What about adding an assignee? eg"Incident 453432 Initial ACK John Doe" Tried this and did not work.
Let me know if have any ideas.