I've made the changes in the main.cf as you suggested but now I cannot receive any emails at all, even from the local domain. I've checked the mailq and the following result came out:
DA34D5804A7 4581 Fri 17 06:04:52 email@example.com
(connect to server1.webdeezsign.co.nz[188.8.131.52]: connection refused)
The above is just one of the emails that is stuck on the mailq and all have connection refused... even if I try sending a loop back email to firstname.lastname@example.org
it stays in the que and won't deliver and then it say "connection refused."