Robot stopped sending e-mail

hi all,

I have built robot on a remote server and my robot was sending e-mail an excel file. 
my robot sends TO:asdasd@asdasd.com and CC: qweqwe@123123.com,zxczxc@123123.com 
but something happened(i don't know what) the people who attached in CC gets e-mail but the person who attached in TO doesn't get an e-mail what possible problem can be here? 

thanks in advance.