[Exim] The Date: header line

Hi,

In Exim Speification Document, section 44.7, says:

"If a locally-generated message has no Date: header line, Exim adds one,
using the current date and time".

I'm trying to put this header in all messages not locally-generated that
it does not have the Date header line but i don't know how.

I suspect that this question was treated some time ago in the list but i
can't find it.

Any help?

Paulo