What you really need to know about email BCC

BCC is short for Blind Carbon Copy. The term dates back to the age of typewriters, but nowadays is commonly used to specify the three different categories of email recipients: TO, CC (Carbon Copy), and BCC.

• TO specifies for whom an email is primarily intended, whereas

• CC specifies all others, if any, with the exception of BCC. CC recipients can see TO recipients and vice versa.

• BCC is a special purpose email send option which can be used in conjunction with TO or CC, clandestine to any, other BCC recipients included

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Blind Carbon Copy tips and tricks: BCC is used mainly for privacy and confidentiality, either on its own or in combination with TO, CC, or both

• to prevent harvesting email addresses for spam;

• for recipients who should not explicitly be made aware to whom else an email has been sent, such as in case

- when recipients do not belong to the same organization, don’t know each other and cannot easily link some recipients and email content;

- of large numbers of recipients (address list);

- when email content is sensitive or politically questionable;

• to conceal additional recipients including, but not limited to, alternative sender email address or for archiving purposes;

but also as for integrity (computer security) purposes

• to thwart mail worms – viruses that send themselves to all email addresses found on a client computer.

The appropriate use of email BCC distinguishes an email savvy person from a novice and can additionally be helpful for your email security and privacy. However, organization’s informal rules, or courtesy may demand the substitution of BCC with forwarding previously sent email by means of TO inserting FYI at the beginning of the text section.

Please note that this article refers to Simple Mail Transfer Protocol (SMTP) [http://tools.ietf.org/html/rfc5321], the underlying protocol of electronic mail transport (covering Blind Carbon Copy), and how it SHOULD be implemented. However, erroneously configured mail servers as well as mail servers brought under control by spammers can lead to BCC recipients unintentionally being disclosed to other recipients or email addresses harvested to send unsolicited bulk email (spam) - section 7.2 of the referenced document explains the flaw in SMTP.

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Writer's own experience