You can blind carbon copy (BCC) people on an email without
the main addressees knowing about it. The
story of the blind carbon copy function is another example of real world processes
imaging themselves in the virtual world.
The simple term "carbon
copy" comes
from
the
days
of manual
typewriters, when copies were
made by typing on paper with several layers. Between each layer of paper was
a thin sheet with carbon on the bottom side, so that when the typewriter keys
hit
the paper, the impact made a "carbon copy" of the letter on the paper
sheet underneath. When you were finished typing a page, you would separate out
the paper and throw away the carbon sheets, almost always getting some of the
black carbon all over your hands.
You could get two, three, and four layer
carbon copy paper, and even some very thin six layer paper. The top paper
got the typewriter ink and looked the best. The top carbon copies always
looked much crisper than the lower copies, as the force of the typewriter key
strike dissipated
through the layers. Occasionally, by accident or design,
an extra carbon copy would be given to someone not on the official CC carbon
copy
address
list.
Because
there was no way the official addressees could know about these extra copies,
they were called "blind carbon-copies" (BCC).
It
turned out that people liked this feature so much they built it into email. If
you put addresses in the BCC field of an email it will be secretly copied to
those addresses, and none of the other addresses in the To, CC, or BCC fields
will
know about it because the BCC
field is not displayed on incoming messages.
Some of the ways that
the BCC field can be used are listed below:
- Plain old secrecy. You can blind copy an email to someone without
the other addresses knowing that you did so to make a third party aware of
an important issue, or
to establish an independent confidential record of your email. However, this
sort of thing is ethically problematic: you should have a good and ethical
reason for not letting
the primary addressee know that the email is being copied to someone else, since
blind copying is basically a form of deception.
- Copying yourself. You can
blind copy yourself to a second email address,
for example to copy an important email from your home address to your work address, or vice
versa.
- Network diagnostics. You can double-check that
an important email makes it out onto the Internet
backbone by blind copying
yourself
on the email at another address, preferably at a different domain name.
If the blind copied email to yourself arrives at your other address, then you
can
be reasonably sure that the copy of the email to the main addressee
you are concerned about made it from your Internet service provider at least
as far as the Internet
backbone,
which assures you that your local system, email server,
and network connection are functioning well. If the intended email still
doesn't arrive at its main destination, then the problem is likely with the
addressee's
network or email server.
- Broadcasting. You can blind copy several email addresses at once in
the BCC field if you are sending the email to more than one person. This
feature of the blind copy is
useful
when
for privacy reasons you don't necessarily want all of the recipients to know
the addresses of the others, such as when emailing an invitation to several
otherwise
unrelated people, or if your email provider has problems and when they recover
you need to send an email to all of your address book warning them that
mail
they sent in the past few days may have been lost.
- Information.
You can surreptitiously copy one friend on a joke email to another friend.
If
you don't enter at least one valid email address in the To or CC field, then
some
email programs will indicate a notation like "Recipient list
suppressed" in the To field,
which tells the recipient at least that there are BCC addresses. If you don't
want that to happen, you need to enter at least one valid email address in the
To field, such as your own address, perhaps with a custom text description like
the following:
To: "Gardening Friends" <jasmin@twenty.net>
Note there is a potential security
flaw in the BCC feature. According
to the conventions of the
SMTP
protocol, all addresses, including BCC addresses, are included in
every email as it is sent over the Internet. The BCC
addresses are stripped off blind copy email only at the destination email server.
Therefore, if the addressee controls their email server or can access it,
they could examine the BCC addresses on every email they receive. SMTP
is
designed
this way for a couple of reasons:
- Efficiency.
It would take a lot more code and processing time to create a unique addressee
list for
each email to each BCC destination.
- Efficiency again.
With this convention, only
one email needs to be sent to each domain.
The email server at each domain reads all of the BCC addresses and
sends a copy of the email (without any addresses) to each of recipients at its
domain.
Very occasionally, an email server will be misconfigured and not strip
off the BCC list on email
it sends to its
local users, revealing the complete blind copy address field to users that receive
the email at that domain. Therefore, BCC is very good but not perfect at keeping
addresses confidential, and should not be relied on for the most critical and
sensitive of communications. To avoid this problem you can always send the
email to the main addressee, and then forward it old fashioned-way to those
that you wish to have a copy.
