Configure IMAP/SMTP on existing Droplet for existing Domain (Ubuntu 20.04)

Hi,

I have a Droplet with a domain/website hosted on it using LAMP. I want to add a webmail server, to be able to send e-mails through SMTP and receive e-mails to forward them to external IMAP clients.

I need to send e-mails for app/site notifications, I send e-mails through simple SMTP scripts. And I need to receive e-mails being sent to my email@domain.com to then forward them to external IMAP clients.

I want to configure it with the minimum requirements, cause I want to have it in the same server where I host my site and I don’t want it to consume too much memory/cpu.

Any recommendations?

I’ve seen this Postfix steps (https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-on-ubuntu-20-04) but I don’t know if it’s what I need.

I also believe that I need to configure some DNS records, such as MX, SPF, DMARC and DKIM. But these are not mentioned on above link.

Notes:

• I do not own any e-mail hosting server, my intention is to create one with this. Is Postfix what I need?
• I want to create e-mail accounts such as: noreply@domain.com, help@domain.com, sales@domain.com
• I don’t want to control an external e-mail account, I want to host it here in this server.

Thanks in advance.