Group Messaging Etiquette:
Group Messages (and really all emails) need to contain an Actionable Subject Line. Ideally you include a Verb and a Noun.
When you message a group, you are often asking people to call, respond, read, scan, follow up, confirm, print, attend, schedule, or any combination of those actions. You often want them to act upon a document, form, event, or process.
It's only fair and respectful to let the recipient know what you need them to do, when they see the email show up in their inbox. A vague subject line necessitates that the recipient read the entire message to know what you want. This significantly decreases the likelihood that your request will be responded to within your timeframe.
Address emails like you would create an a to-do item for the recipient. Brevity and clarity are also appreciated.