I was always under the impression that only the recipient who was BCC'd was blind? You can see if and email that was addressed to yourself was BCC'd to someone else but they can't see any other recipients?

A consultant I work with sends out a monthly newsletter and it is BCC'd to all. Therefore none of us know who their other clients are.

I've always thought that BCC addresses could not be seen by anyone, including those in TO and CC.

Perhaps your email was an original that was Forwarded ?

Here is an example email addressed to nine people:

Ahmed, Barry and Carol can all see that the email was sent to Ahmed, Barry and Carol for their attention and they can also see that a copy of the email was sent to Darren, Elaine and Fred.

Darren, Elaine and Fred can all see that the email was sent to Ahmed, Barry and Carol for their attention and they can also see that a copy of the email was sent to Darren, Elaine and Fred

Gunter, Harriet and Ian can all see that the email was sent to Ahmed, Barry and Carol for their attention and they can also see that a copy of the email was sent to Darren, Elaine and Fred

Nobody can see that the email has been sent to Gunter, Harriet or Ian