Help members identify emails they receive from the group. The text you add in the prefix will appear in brackets before your subject line.
If you want to add a prefix to the subject line of all the messages sent to your group, go to the Group Settings, choose Email Settings and type in the text you would like to precede all of your messages in Subject Prefix. Click Save Changes at the bottom.
Pro Tip: If you want [ ] or { } to be added around your text be sure to add them.