[Exim] sender concept

Hi!

What is the definition of "sender" concept for Exim (3.16)?
Speaking more precisely, what does Exim try to lookup in the DBs
specified in "sender_reject" clause? It does not look like the
address extracted from "^From:" field. Is there any way to make this
lookup based on "^From:" field avoiding to use filters?


Thanks!
/Sergey

PS: I could not find this information neither in docs nor in FAQs.

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Sergey A. Maslyakov
2:5030/1024@fidonet