I am using external mail server but store emails keeps sending to localhost email

Hi,
First of all I am sorry but I think this is more of a VPS and Panel issue.
But I was kind of hoping someone can still help me here since I am now running an unmannaged server

I am running on VPS server with Vestacp Panel
I am using an external mail server via MX record.
I am successful of receiving emails to the external mail server.

When new orders, new customers, customer enquiry etc etc has added, the emails are sent to the store email. The problem here is that it is still sent to the local mail server. Not to the external mail server.

I still have the email address added in my mail settings in vestacp if that is an important information for this problem. Should I delete this?

So right now I am checking the local email and the external email side by side for new emails.

But this does not resolve my problem.


Now for an opencart related question. Do you think that opencart is sending this to local host because of Mail email setting?
Rather than using the SMTP settings?

Details:
Centos7 OS
vestacp 0.9.8-17 Panel
OC 2.3.0.2

Just to confirm, have you setup SMTP settings in Opencart?