When someone will send emails to the account xxx@abc.com, niether it bounce nor it is delivered.

I have checked for the log and found below entries, could anyone assist me in this regard!

2005-11-30 08:38:04 H=(smtp.xxx.net.mx) [xxx.xxx.xxx.xxx] F=<automotrizspa@rrrrr.net.mx> temporarily rejected RCPT <xxx@abc.com>: Could not complete sender verify callout

I am using EXIM mail server.