[Exim] sender address must exists !!!

Hi Everybody

I'll try to explain my problem using an example:

1- My server is configured to be a relay for all the emails coming from the
domain test.com

2- The email address example@??? doesn't exist

3- Exim is allowing to send messages like this:
    From: example@???
    To: relaytest@???

Can Exim check first if the email address exists and then send or reject the
message ?

Regards in advance

Javier