Automatic cases assignment to groups

Your suggestion is great. Thank you.

I have a new question now: due to the automatic assignment, the following email is sent.

[color=#ff0000]Admin has assigned a Case to the User1.
Object: Test
Priority: High
Status:
Description:
Test
You can see this Case clicking on this link.[/color]

How can I customize this email? This is not in the list of the email templates