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How do I view the list of BCC'ed recipients on an email I've received?

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Summary: The list of BCC'ed recipients is not incluced in emails, so there is no way of determining if and who else the email was sent to.

I want find the list of "undisclosed recipients" of the email I've received in outlook. Is there any way?

"Undisclosed recipients" is often placed in the "To:" line by some mailers when the email being sent has no entries in the "To:" or "Cc:" lines. The sender has used the "Bcc:" feature of email to send the email to one or more people, without revealing who they are.

So how do you find out who they are?

You don't.

That's what "undisclosed" means. The information about who the email was sent to is not included in the email. There is simply no way of determining if it was sent to anyone else and if so, who.

Now, to be complete, I do recall hearing about some old email programs - and we're talking ten or twenty years ago - that got the whole concept of "Bcc:" and undisclosed recipients wrong. They included the Bcc'd recipients in headers that everyone could read if they knew how. But that was a serious bug and has long since been resolved.

Today's email programs simply don't disclose "undisclosed recipients".

It would be wrong to do so.

Related:

Article C2227 - November 19, 2004

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Recent Comments
44 Comments

At what point is the BCC information stripped from the email? Do two separate packets go out completely stripped of the information, or does it happen at the mail server/ISP? How do spam programs know (if they do) that there is a long BCC list?

Posted by: Krissy at January 9, 2008 6:58 PM

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Justin: then the sending mail program was not handling BCC
properly or we're not really talking about BCC.

Krissy: the BCC information is stripped off by the sending
program. It tells the mail server who to send the mail to,
but does NOT include the headers that would normally be
included in the message that would also contain that list.


Leo


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Posted by: Leo A. Notenboom at January 10, 2008 3:02 PM

In Yahoo - if you want to see the BCC list for something that YOU sent.. Right click on message - choose "Veiw full headers". This is for the new Yahoo mail - not sure about classic yahoo mail.

Posted by: R at January 13, 2008 6:00 AM

Leo:

There is a known bug in Exchange 5.5 through 2003 SP1 that if a non Outlook MAPI email client is used to forward or reply to an email with BCC recipients, the BCC recipients will be revealed. How do you explain that in light of your statement that the BCC information is stripped off by the sending system? Do you have reference for a kb article or otherwise that defines this in MS Exchange? This is a mission critical issue for me - thanks for any insight you can offer.

Posted by: wtkjd at January 17, 2008 8:35 PM

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I'm not sure what I'm supposed to explain. You said it
yourself, it's a bug, it's not supposed to happen. BCC
information should never make it past the sending server,
and ideally never even leave the email client.

Leo


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Posted by: Leo A. Notenboom at January 22, 2008 5:37 PM

In Outlook Express: If you are the sender of the email with BCC recipients you are the only one able to see that list by:
Right clicking onto the email in the Sent folder, select Properties. Click on the Details tab and the list of BCC'd recipients will be shown to you.

It is always there for the SENDER only. Recipients are not stripped.

Posted by: Meredith at February 27, 2008 12:48 PM

I have Outlook Express and need to see the BCC recipients of e-mails I have sent; I have tried the above method of checking the details tab on the properties of the e-mail, but it doesn't work; the BCC remains hidden. Perhaps Microsoft has removed this entry of the panel in a recent update. When you can't see to whom you sent your own messages, data protection has surely gone too far...

Posted by: Bernard Winchester at June 8, 2008 4:13 AM

In Outlook 2003,
Open the sent message from the Sent folder;
View => Header (toggles on/off)
bcc will appear

Posted by: Steven Potter at September 23, 2008 7:36 AM

Leo, I think you are not answering the question that was asked, "I want find the list of "undisclosed recipients" of the email I've received in outlook. Is there any way?". Take a look at following link http://crypto.stanford.edu/portia/papers/bb-bcc.pdf

Fascinating. First, let's be clear: this is fairly irrelevant to most people, however, as it applies ONLY to encrypted email.

The paper outlines a flaw in how many mailers create encrypted email. It's not a direct exposure of email addresses, but rather encryption tokens that could be traced back to email addresses.

And to be even clearer: it's a flaw in the system - BCC is not supposed to be exposed.

Thanks for the pointer.
- Leo
25-May-2009

Posted by: Chris at May 24, 2009 9:03 AM

I understand that you can't see anyone in the bcc: list if you are the recipient, but what about if you're the sender?

I sent an e-mail to a long list of recipients in the bcc: field but forgot to include an attachment. how can i bring back up the e-mail, add the attachment, and resend it to all the same recipients?

Thank you!

It depends on the email program you use. Basically, just open the sent mail, and it'll either be there or it won't.
Leo
19-Sep-2009

Posted by: mark raulston at September 18, 2009 12:42 PM

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