Many people probably simply fill in the "to" field in their emailer every time they need to send a message. But the other options are there for a reason. When used correctly, these options can give people useful cues and avoid leakage of information that is none of other people's business.
Keep in mind that this (mostly) just my opinion. I don't think that you're using email the "wrong way"—whatever that would even mean—if you don't follow these tips. But at the same time, I think you'll have serious trouble finding anyone who is annoyed by them.
This is part one of a planned multi-part series on email.
The Cc field can be used to indicate that you are sending the message to a specific person and merely want to notify someone else that you've done so, or if one of the recipients is less important than the others (in terms of responding to the email, of course). Many email clients automatically use the Cc field when activating "reply to all", only filling in the To field with the name of the person to whom you're directly replying.
Cc doesn't actually have any impact on the way the message is delivered, except that some email addresses appear under the "Cc" heading instead of the "To" heading; it's only a convenience to be used however you want to. For all the computer cares, you could establish guidelines in your office that if you Cc someone a message, that means you're in trouble and they need to telephone you immediately. But the "less important" or "FYI, I sent this message to so-and-so" interpretation is pretty much universally understood among serious email users. Like putting people's emails in the To field, every recipient of the email can see all the people you Cc'd a message to.
Sometimes you need to click a link or button marked "Add Cc" in order to see this field.
By the way, "Cc" stands for "carbon copy", though you'll have a difficult time finding an email program that actually says that anymore.
Bcc stands for "blind carbon copy"—when you use it, nobody sees the email addresses in the Bcc field except you, but everyone still gets the email.
Not using the Bcc field properly is one of the things that I actually do get annoyed with people about on occasion. This is why: say someone sends a wedding invitation to 200 people using the standard To field. Now, everyone who received that email can see the entirety of the To field. If I'm a recipient of this message, my email address has now been given to 200 people that I likely don't even know, without my consent.
There are plenty of uses for the Bcc field, but the most important one is this: always use the Bcc field when sending email to multiple people who do not know each other and do not need to write each other back. If all you're doing is sending an announcement to people, the only person they would possibly care to write back to is you. (If they did want to write someone else on that list, they would already have his or her email address.)
Another use is stealth: say I'm sending a message to someone that's somewhat confidential. I may want someone else interested to see the message and what's going on, but I don't want the main recipient of the message to see. This can be a bit dishonest if you use it the wrong way, but there are plenty of perfectly reasonable situations in which you might want to do it.
In the old days, it was common to blind-copy yourself if you wanted to keep a copy of the email. Now any email program worth its salt will store a copy in the "sent items" folder automatically, so this use has largely fallen by the wayside. In the rare situation that you're sending an email from someone else's email account, you might still want to do this so that you have a copy on your own account.
Sometimes you need to click a link or button marked "Add Bcc" in order to see this field. Additionally, some email clients will not allow you to send a message with only the Bcc field filled in (nobody in the To field); if yours won't, established practice is to put your own email address there, as this doesn't single anybody out and doesn't give away any information that people didn't already know.
Soren "scorchgeek" Bjornstad
If you have found an error or notable omission in this tip, please leave a comment or email me: firstname.lastname@example.org.
Copyright 2012 Soren Bjornstad.
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