Exemplo do Sendmail
vim /etc/mail/greylist.conf
list “my network” addr { 127.0.0.1/8 192.168.100.0/24 192.168.200.0/24 192.168.150.0/24 201.24.55.12/26 200.173.16.230/28 202.7.162.74 179.14.182.190 }
vim /etc/mail/access
Connect:202.76.163.71/30 RELAY
202.76.63.174 RELAY
Connect:201.76.163.74 RELAY
makemap hash /etc/mail/access.db < /etc/mail/access /etc/init.d/sendmail restart