DEAR MISS MANNERS: When, if ever, is it appropriate to use “reply all” in group emails? Only when asked to? I find it annoying when people reply to all.
GENTLE READER: The proper time to reply to everyone is when the answer can reasonably be expected to be of interest to the group -- and when your response respects the context, tone and subject of the original.
A company email from the boss explaining a new policy is not an invitation to tell everyone you object. A serious email about the water being shut down in the building is not an invitation to make a joke about the cleanliness of said water. And an email from your cousin announcing the date for the family reunion is not an invitation to open a debate about who is hosting Easter.