[Exim] Copying mail to another mailbox

Hi,

I need to set up a configuration so that the boss gets a copy of every
mail his employees receive. I thought of a rewrite condition:

*@domain $1@domain,boss@domain E
boss@domain boss@domain E

The second line should care for the boss not receiving his own mail twice.
Are there any mistakes in my kind of naive approach, should I rather use
a more sophisticated version using the system filter as in Q9817,
"I need to take copies of all incoming and outgoing mail for certain
users. For each user there may be a different monitoring address."?

greetings,
Jens.
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