Edit
vi /etc/exim/exim.conf
Comments lines
# drop condition = ${if isip{$sender_helo_name}}
# message = Access denied - Invalid HELO name (See RFC2821 4.1.3)
centos6
service exim restart
centos7
/bin/systemctl restart exim.service
# drop condition = ${if isip{$sender_helo_name}}
# message = Access denied - Invalid HELO name (See RFC2821 4.1.3)