Blind Carbon Copy (BCC) – How to send blind carbon copies of your emails

The BCC field is one of three address fields available in the email header. It can be used to address email recipients in addition to the To and CC field.

We explain what BCC means, how you can use it in email correspondence, and when it’s best to avoid entering BCC recipients.

What does BCC mean?

The abbreviation BCC stands for blind carbon copy. The term is derived from carbon paper that was often used to create a copy of typewritten documents.

Unlike the carbon copy feature (CC) – in which a copy of a message is sent to CC recipients visible to everyone involved in the correspondence – a BCC recipient is kept hidden from other addressees.

Technical implementation of the BCC field

The BCC feature is not standardized. Information in the BCC field is often processed very differently by email programs and mail servers, depending on the implementation.

The following procedure is typical:

  • Before the mail server responsible for your mailbox sends a message to the recipients you entered in the To, CC or BCC field, the BCC field is removed from the email header. Contacts addressed via BCC are treated like normal email recipients and receive a copy of the message, just like CC recipients. As is the case for all other addressees, BCC recipients can view both the contact addresses in the To field as well as in the CC field. However, they can’t see the addresses of other BCC recipients since this information is not forwarded to any of the recipients.

If the BCC field is removed from the email header once the email is sent, BCC recipients are unable to see that they’ve received the email without the knowledge of the recipients in the To and CC field. There is therefore a risk that a BCC recipient responds using “Reply to All” and thereby reveals themselves.

Even if most mail servers work in this way, it’s also possible that BCC fields are processed differently in individual cases.

  • In some instances, although the information in the BCC field is deleted, the BCC line in the email header is still transmitted as an empty field. A recipient may then realize that third parties have been addressed in the BCC field – but they won’t know who the BCC recipients are.
  • It’s also possible that the BCC line is only removed for the recipients in the To and CC field. Conversely, BCC recipients may receive the email with the BCC line and either find only their own address there or – in the case of especially poor implementation – all contacts addressed via BCC.

The BCC feature in practice

BCC recipients receive copies of emails addressed to other recipients, without the actual addressees being informed. This may sound like questionable covert behavior at first, but it is quite justified in certain communication situations – particularly when the email addresses of BCC recipients have to be protected.

There are three primary motives here:

  • Data privacy: Only add contacts to the CC field if they agree to their email addresses being shared with all recipients.
  • Spam prevention: Email circulars that contain all addresses of a mailing list in the To or CC field present easy targets for spammers.
  • Virus protection: Protect your contacts from malware by not revealing their email addresses to other recipients in the To or CC field of circulars. Cyber criminals also sign up for newsletters or advertising mails and exploit email addresses that are carelessly shared for their own nefarious purposes.

The BCC field is ideal for use with email circulars to a large group of recipients.

Imagine you’d like to send Christmas greetings to your customers, business partners, and suppliers. To alleviate the task, you opt not to send out individual emails, but instead send each contact the same message. Would you address all your contacts in the To or CC field, visible to all? Probably not. To protect your customers’ data and keep your business relationships hidden, you should use the BCC field instead.

But data privacy isn’t only relevant to the business sector. A teacher, for example, should also avoid adding contact lists to the CC field and instead address recipients via BCC when emailing information to the participants of a parents’ evening. This approach protects the recipients’ data and prevents email addresses from being disseminated unchecked – whereby they could potentially end up in the hands of spammers.

However, blind carbon copies are unsuitable for internal communication processes.

Companies also engage in active email correspondence internally. Here, email copies can inform colleagues and superiors about workflows and promote transparency. In contrast, the BCC feature can be detrimental to transparent communication.

Just imagine you are discussing a sensitive issue by email, but your conversation partner not only replies to you but also to a third party via BCC without your knowledge. You would likely feel deceived or at least ask why the other recipient was kept secret.

Therefore, we recommend refraining from using the BCC feature within your organization. The CC field is a better choice in this context. That is unless you deliberately wish to keep certain colleagues out of longer email discussions. The reason for this is that BCC recipients are not automatically addressed using the “Reply to All” feature. If you’d simply like to let a colleague know about your email without including them in follow-up correspondence, it may be a good idea to add them to the BCC field and explicitly inform other recipients about this in your message.

Advantages and disadvantages of the BCC feature

Advantages Disadvantages
The BCC feature protects the privacy of BCC recipients, and, as an alternative to open mailing lists, helps to reduce spam and the spread of malware (when used correctly). Recipients of a blind carbon copy are not usually able to tell that they were addressed via BCC.
The BCC field enables you to involve anonymous third parties (such as lawyers or superiors). A BCC recipient can engage in communication at any time via “Reply to All”, thereby revealing their status as a secret participant.
  The BCC line in the email header is not processed in a standardized way, and this could lead to unintended effects depending on the mail server or email program.
  The BCC field is detrimental to transparent communication.
  Addressees who are not informed of other recipients often consider the use of the BCC line to be a breach of trust.

Refrain from using blind carbon copies for the sake of transparent communication, unless it is clear to all recipients that third parties are able to read the message – either because it concerns an email circular or because you explicitly notify them about BCC recipients.

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