Have you ever been on an email chain, conversing pleasantly with colleagues and/or friends, and been suddenly informed that you have been “moved to BCC”? Was the announcement a tad startling? Maybe a bit confusing? Did the tiny part of you that remains a self-conscious tween wonder whether you had really just been informed that the party was over, while the party was so obviously still going on?

Such fears are, to an extent, well founded: You were, indeed, forcibly ghosted. To the extent that CCs and BCCs are email’s method, as the professional-resources site Levo puts it, “of including multiple recipients in a hierarchical way,” you were demoted, and extremely publicly. But that’s also to say that, in this age of incessant conversation and information overload and weaponized risotto recipes, you were shown the greatest gift another human can offer to another, on email: You were given the present of non-presence.

Here’s the quirk of email that makes “moving you to BCC” such a mercy: When someone replies-all to a conversation that contains both CCed and BCCed parties, the CCed folks will receive the reply … while the BCCed parties won’t. So to move someone to BCC in an email chain is to ensure that they won’t be part of the conversation going forward. And to inform them of the move is simply to be transparent, to all involved, about the upcoming silence.

Paul Argenti, a professor of corporate communication at Dartmouth’s Tuck School of Business, gave me the following example of the canonical “moving you to BCC” scenario: Say Argenti introduces two people over email. Ideally, if one of them doesn’t ruin the whole vibe with an awkward “nice to e-meet you,” the two continue the conversation between themselves. Argenti, here, doesn’t need to be part of the back-and-forth that ensues—in fact, he would very probably prefer not to be. So one of the recipients of his initial email, thoughtfully recognizing this fact, removes him from the conversation. “Thanks, Paul (moving you to BCC),” that person might say.

Argenti, in his scenario, will be grateful to the (re)mover. “Moving you to BCC,” Argenti told me, is essentially a shorthand for saying, “I know you really don’t want to hear this, but I do want you to know that we’ve gotten in touch, and thank you very much.” Bim, bam, blessedly silent boom—politeness all around. It’s so elegant. It’s so merciful. And a similar approach can be used when a conversation that started with many people has narrowed to require input from fewer participants. Some thoughtful soul will take it upon themselves to do what people, email being what it is, cannot always do for themselves: remove them from the chain, with its inbox-clogging messages and its nagging attentional requirements. That person will have done their colleagues a solid, and also acknowledged a profound truth of modern life: that taking one for the team will occasionally mean taking people off the team.

Here, though, is another quirk of email architecture, one that can make “moving you to BCC” so confusing for those on the receiving end of it: “Moving you to BCC” is a future-oriented courtesy, one that operates in a conditional framework. “If this conversation continues, then you will not be part of it.” So to have been moved to BCC is to have been liberated, but only almost; until the next round of replies, you will exist in a kind of epistolary purgatory. It’s awkward, for sure: You’re there, but you soon won’t be, and the person who has made that decision on your behalf is now informing everyone else about your imminent departure. There you are, maybe and maybe not, caught up in Schrödinger’s email field.

And yet: It’s worth it, because soon you will be rendered blissfully ignorant of the rest of the chain’s proceedings. You will have been disappeared, out of courtesy. The “moving you” move is one example of what Daniel Post Senning, the great-great-grandson of Emily Post and himself an etiquette expert, calls “emerging etiquette”: conventions and courtesies that arise to fit new cultural environments. Some conventions, he told me, are fairly constant—table manners, say, since forks and knives probably aren’t changing anytime soon—and so are broad values like honesty, and consideration, and respect, which will always underscore our notions of courtesy. Other elements of etiquette, though, change with new mediums and technologies, bringing questions and confusion as they do. Is it polite to include a period at the end of a text-message, or extremely passive-aggressive? Do smartphones have a place at the dinner table? Etc.

And conventions that arise around communication, in particular, Post told me, “are some of the manners that change the most rapidly and that require the most work and attention to stay current.” When our environment—technological, and otherwise—is changing, our expectations of each other will change along with it. Our sense of politeness will change, too.

“Moving you to BCC” is one more convention that has arisen as a response to an evolving world. It’s a coded acknowledgement of a widespread technological situation: Many of us are, at the moment, drowning in emails; in 2012, per one estimate, the average person wrote a novel’s worth of emails in a year. And newsletters, ads, spam, important communications from fellow humans we know and love—there they all are, jumbled together, competing for our time and attention, as unread-email counts rise and Inbox Zero goes from an aspiration to a pipe dream. It’s a mess. But it also helps to explain why the BCC is sometimes understood to be an acronym for the “blind courtesy copy”: Deploying it is, in the end, a courtesy. It allows you to give another person that great, and ever more rare, gift: silence.