[Exim] verify sender/callout

Hi,

I use in my Exim 4.23 the option:

require verify = sender/callout

This works fine with remote hosts, which send and receive SMTP
connection for the user that is verified.
But sometimes the SMTP connection comes from a host, which only sends
emails via SMTP but not receives any.
In such case the callout does not work. Is it possible to configure
Exim to make callout verification using the MX value instead of the
host IP/name the SMTP connection comes from?

Regards,
Robert Heron