I never have.
One of the MUAs shipped with Innosoft's PMDF product makes it easy to create
such messages. As a result I've received (and sent) many of them over the
years. Some of the old integrated office suites generated such messages and the
construct is of use in workflow environments where it is important to keep
track of all the authors of a given piece of work.
Amusingly, I've gotten exactlly one interoperability problem report from the
practice - from Dave Crocker. (I believe he switched clients as a result.) On a
side note, in the specific case of the old office suites, the practice they
engaged in that was really difficult to accomodate was the fairly common
practice of every recipient address in the header, even when this ran to tend
of thousands of addresses. Quite a lot of code stutters a bit when presented
with a multi-megabyte header.
It shouldn't too hard to research though.
Really? Then by all means explain how you proposed to demonstrate such a
negative. Vast amounts of email that's sent and received is limited to specific
usage enclaves and makes it into no publicly accessible archives. (And there
would be hell to pay if this weren't the case - this class of stuff includes
email-based workflow systems used between financial and medical institutions.)
I guess we could ask if there might be a future use case?
I see little value speculating on future use cases where there are obvious
present day ones.
Ned
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