[exim] Sender Verification Results

When sender verify fails, What veriable contains the result string that
is returned. I'm trying to make sebder verification smarter so that the
following does mean failed.

telnet relay.amcity.com 25
Trying 65.213.145.14...
Connected to relay.amcity.com (65.213.145.14).
Escape character is '^]'.
220 ******************************
helo ctyme.com
250 relay.amcity.com
mail from:marc@???
250 Ok
rcpt to:mveloz@???
450 <mveloz@???>: Recipient address rejected: Service is unavailable