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Re: [PLUG] BCCs potentially exposed
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> I just learned on the Evolution list that some servers add the header
> Apparently-to: identifying BCC recipients.
I don't think that is true. Some servers (including Sendmail, I
think) add 'Apparently-To' to identify the *envelope recipient* when
there is no 'To' field in the message.
> In Windows, I have always used Pegasus as my MUA. Pegasus sends out
> separate mails whenever there is a BCC, to insure security. I thought
> all MUAs did this.
Even if they did do that, it would not 'insure security'. The
'Apparently-To' field could be (and sometimes is) added by the remote
MTA. There is nothing to stop this MTA from adding a field that says
Thought-you-might-like-to-know: Arthur Alexion also sent mail
today to Miss Audra Scarlett with subject
"CONFIDENTIAL: you left your underpants at my house"
or whatever else it likes, regardless of whether the message was sent
separately from others or not. Here the remote MTA has helpfully
linked your message concerning the FY 2003 budget with an unrelated
one concerning Miss Scarlett's underwear.
> Are the other Linux MUAs broken like Evolution?
There is no officially recognized set of "Linux MUAs". There are
probably dozens of different MUAs that can be used with a GNU/Linux
system. So there is no way to answer this question without
enumerating the behavior of every one of the dozens of programs that
you might be interested in.
In any case I think you may be mistaken in assigning the blame to the
MUA here.
For example, consider the 'qmail-inject' MUA. qmail-inject properly
removes the Bcc: line from the message before inserting it into the
qmail local queue. If there are three local recipients and three
remote recipients, there will be two copies of the message in the
queue, one for the local recipients and one for the remote
recipients. However, both copies will be identical.
>From there, the qmail MTA will transmit the message separately to
every one of the six recipients.
The remote MTA still might add naughty or scurrilous headers to the
incoming messages. This has nothing to do with qmail-inject.
> Is it a flaw in the standard that permits this?
That is a judgement call. I would say that it is not, that it is a
quality-of-implementation issue in the remote MTA.
> In my work BCCs and their privacy are critical. It's a "don't use this
> software for serious work" issue.
I hope this message contains specific information that makes it easier
for you to evaluate MUAs.
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