[exim] use system filter to create a copy of each outgoing m…

Dear all,

I have a user who does SMTP AUTH to send out mails via my server. I
would like to get a copy of each message he sends (with his consent, of
course ;)

This is what I have in the system filter:

if ($authenticated_id is "hisUserName")
then
unseen deliver my@???
endif


This works well except for one case: If mails to my@??? can't be
delivered, there's no retries. The reason is that unseen makes this a
non-significant delivery.

I can't remove the unseen, this would stop the mail from being delivered
to the actual recipients.

Do you have a recommendation how to create a copy and ensure that
there's the usual retries when the copy can't be delivered?

Thanks for your help,

Martin