I want to understand the points below:
1- to enable public users out on the internet to send email to my organization, I should register MX and A record with the ISP. Correct?
how do they show at the registar?
A : MyCompany.com 220.127.116.11
MX : Mycompany.com
2- once the A and MX records registered, public users can send email to Mycompany.com , and it will come to my public router interface 18.104.22.168 , and from there how does it finds the route to my exchange server Mailbox??
3- if a public user , send email from Yahoo.com to Mycompany.com, I wonder if it goes through CAS server, or just from Hub server to Mailbox server?