Setting up and configuring an entire email server in the cloud on Ubuntu(Linux) for a website

So for this example I setup an email server in Ubuntu on a cloud for a testing website I created. The process builds upon previous examples. So for this I started with installing Apache and PHP on the virtual machine to begin the installation and configuration of all the additional components.

First I installed Postfix which serves as the MTA(mail transfer agent). This is the software responsible for delivering and receiving the emails. Then I installed Dovecot as an MDA(mail delivery agent) which then more specifically delivers the emails to/from the mail server. At this point I now have an IMAP/POP3 email server and am going to install SquirrelMail on the email server to have a simple interface to manage emails on my server.

Here I added postfix to the server above and below I am confirming the service status. Everything looks good for the next steps.

Below I now have confirmation that Dovecot is active and running. The email server is up at this point. 

I did a code review on SquirrelMail to make sure the configurations are correct for my server. I just had to add a few read/write access modifications to the server for this to work correctly. Also for now since this is a private email service random users can not sign themselves up. I as the admin create users directly on the server as you would normally have for a company's external email login for employees.

I then tested to confirm that I can receive emails from my gmail account and I am also able to send emails to other users with accounts on my server. I created a test account of 'tester' and another of 'squirrelone'. Their respective email addresses are now tester@slabj.com and squirrelone@slabj.com. Here 'squirrelone' has received test messages from 'tester' and myself from my gmail address.

And that's it. I have an Ubuntu cloud based email server correctly setup and configured for a specific domain I created where people or even other servers are now able to send and receive emails.