I have a customer, who uses a host that seems to have many SMTP servers, and every week or two,
he starts getting bounce messages when sending to me, that the current SMTP server is on some RBL
and the email cannot be delivered to me.
I can see in WHM, how to whitelist an IP, or range of IPs, but can I just whitelist all email addressed
from *@domainx.com to prevent RBL checking?