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.

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.

The BCC feature is not stand­ard­ised. 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.

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 realise 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.

BCC re­cip­i­ents receive copies of emails addressed to other re­cip­i­ents, without the actual ad­dress­ees being informed. This may sound like ques­tion­able covert behaviour 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 or­gan­isa­tion. 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.