Re: [Exim] The Bcc Issue

I can see only one solution to the Bcc issue. The MUA must decide on what goes in
the header. If it is to include a Bcc then it must generate at least two copies of
the message, one for the Bcc recipients (or possible one for each Bcc recipient) and
one for the others. All copies must have the same Message-ID so that threading can
work.

A MTA has no way of knowing whether to strip a Bcc header because it cannot reliably
compare the envelope recipients to the Bcc recipients, since some re-writing may
have taken place on both at some point along the message's transit. In principle
the first MTA could expect the envelope and header to match, but an MTA has no way
of knowing if it is the first.

Phil.
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Phil Chambers (postmaster@???)
University of Exeter