[exim] System Filter for Outgoing Mail Without Repeating Any…

I have a system filter that BCC's all outgoing emails to an archive
address. Currently, it forwards a copy of each recipient to the archive
address which results in several duplicate copies of the "same" email.
The archive address is monitored in real-time and I need to eliminate
duplicates for an ongoing business process.

Does anyone have a solution to unseen deliver only one copy to this
archive and still deliver the message to all recipients?

if first_delivery
and ($header_from: contains "@mydomain.com")
and not ("$h_X-Spam-Checker-Version:" begins "SpamAssassin")
then
unseen deliver "outgoingemail@???"
endif

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Thanks,

Justin Granger
Director of IT
Director of Software Development
V: 972.808.7463