BCC and Gmail

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This topic contains 2 replies, has 3 voices, and was last updated by Nick Francesco Nick Francesco 3 years, 7 months ago.

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    Here’s something that I just ran into this week, although a search of the web shows it apparently has been noticed by some people for some time.

    I sent out an email to several people, and used the BCC: to protect the various recipients email addresses. In such a case I normally include myself as an addressee. Much to my surprise, when my copy came back to me, the email header had a BCC: line with everyone in the distribution list shown.

    In this case, I was using Thunderbird, and it uses Gmail as my mail server, both inbound and outbound.

    I guess I assumed that Gmail, when it passed the email on to the various destinations, would be stripping the BCC information off. But that apparently isn’t the case.

    Some testing here showed that when one of those emails was passed from Gmail to Frontier, that the information was still present.


    I thought it was the MTA’s job to convert a message containing a Bcc line into new messages with the Bcc line removed, but apparently that’s debatable.

    That page mentions that some MTAs will leave the Bcc line in only the sender’s copy, so maybe for other recipients it is being removed?

    Here’s a Thunderbird support article. It says that Bcc recipients are required to be hidden from To and Cc recipients, but not necessarily other Bcc recipients.

    Since the MUA is a factor, maybe there’s a difference when sending from Thunderbird versus sending from the Gmail web interface?

    Nick Francesco
    Nick Francesco

    Just tried it. Sent from Address A in Web Gmail to Address B in TO: and Address A, B, and C in BCC:.

    Address A sees BCCs, but it’s the sender.

    Addresses B&C in Thunderbird see themselves in BCC, but no one else. This is borne out by viewing the source of the message in Thunderbird.

    Your mileage may vary.

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