Send System Email Without Postfix

I'm using Email service offered by the Domain Registrar to send and receive emails for websites hosted on CWP VPS.
The Registrar provided MX, CNAME, SPF and DKIM records to add to the host DNS manager for each domain which I did and email services are working as expected.

After that, I have stopped Postfix server as well as other Mail related services in CWP. Now as expected, I'm not receiving the system generated emails like LFD notifications, SSH login to the admin address. Which I want to continue to receive.

I've checker following CWP wiki article and a few others.
https://wiki.centos-webpanel.com/how-to-setup-remote-smtp-server-as-relay

But I could understand that, in order to receive system emails, I have to run the Postfix server. Is there no other option to perform the same without the need of Postfix as I have running VPS on low memory.

I thought like entering CNAME, MX, SPF, DKIM records for the hostname as its the subdomain of the main domain name. But there is no such DNS configuration file for the hostname within DNS functions. I'm quite less familiar with DNS functionalities.

How do I receive system emails without the involvement of Postfix?

Thanks

I have the same question.
All websites are using external SMTP, but i have to keep Postfix active just to receive system emails.
Would be great if we could also use an SMTP alternative for the panel itself.

postfix is mail delivery service it need to be on, else sendmail and other will not work.