In the many years I have been online, I have only very rarely deliberately clicked "reply all" when repling to email which includes lists of people or groups.

The problem is that I get a lot of email and sometimes I am in a hurry, and there's an insidious newer form of group email which does not require clicking "reply all" to send what you thought was a personal reply to one person and have that go instead to countless unknown people.

It will say who it's from, and appear for all intents and purposes to be an email from that person -- even showing his email address at the top. But if you write a reply and then click reply, unless you are careful enough to read all the way down and think about what "reply-to" means, your "answer" could be going to dozens if not hundreds of people, or even a bulletin board.

Here is a perfect example. (With identifying information removed, of course.)

Subject:   Our discussion last night

From:     Joe Yourbuddy <yourfriend@nowhere.com>    
Sent:     Mar 11, 2011 02:22:22 PM
To:     <xxxxx@xxxxxxx.com>
Reply-To:     admin@groupthink-group.com

It may look like it's from "Joe Yourbuddy," and it was in fact written by him, but your reply will be seen by everyone at wherever "reply-to" is.

It's the equivalent of "Reply All," except you cannot avoid it by avoiding "Reply All." You have to watch carefully and interpret the meaning of the "Reply-To."

Anyway, a WSJ piece notes the obvious -- that "Reply All" is dangerous:

You know that feeling: You hit Send--and your heart nearly stops.

This shouldn't still be happening. After almost two decades of constant, grinding email use, we should all be too tech-savvy to keep making the same mortifying mistake, too careful to keep putting our relationships and careers on the line because of sloppiness.

[...]

...Reply All is dangerous. It makes us feel in the loop. And it can be a way to toot our own horns. Never mind that we hate how group emails multiply like rabbits in our inboxes. "Many people lean toward covering their rears by overinforming their bosses and colleagues," Dr. Wallace says. "They can then say, 'Well, I cc'd you on all that debate last month...Didn't you read it?' "

Why don't email programs have a "dummy button" that pops up when we hit Reply All and asks, "Are you sure?" There are applications for that, such as Sperry Software's Reply to All Monitor.

I like the idea of the software, and I wonder whether it addresses the fiendish "Reply-To" problem. (I can't tell from the site whether it warns you that "reply to" might mean posting to a public board without knowing it.)

These days, it isn't enough to merely beware of clicking "Reply All."

You need to beware when clicking "Reply."

When in doubt, avoid reply!

MORE: The bottom line to remember -- "Reply To" is not the same as "From"!

The former controls over the latter!