Please make sure to put a cover sheet on your TPS reports.
Team,
Please make sure to put a cover sheet on your TPS reports.
Everyone,
Please make sure to put a cover sheet on your TPS reports.
Good Afternoon/Morning,
Please make sure to put a cover sheet on your TPS reports.
Staff,
Please make sure to put a cover sheet on your TPS reports.
I just quickly browsed through my emails I've received this year (coworkers, customers, vendors) and that covers all the ones I've received. All of those are perfectly acceptable.
I wouldn't be personally use "guys," "gals," or "guys and gals" in a non-friend situation.
All of those comes across far more formally than "guys", they remind me of a written order from a military officer (source: 10 years in the Army). For me "guys" seems far friendlier.
So what's the acceptable format? "guys, gals, and... others?"