Send Only SMTP Server using Postfix and Mailutils

Get a server from GCP, Azure, AWS, Digital Ocean or other and run
$ sudo apt-get update
$ sudo apt install mailutils
A postfix config screen should appear,
select 'internet site'
enter the mail servers name, it should be something you've already setup in your existing DNS providers name server elsewhere. for example. I set up an A name record for smtp.seanwasere.com and it points to the IP Address of the server I am using in this video and got from digital ocean.
Digital Ocean : m.do.co/c/23d2... ($50 Free Credit for 30 Days)
Alternatively, you can I also have a Hetzner Cloud coupon where you will receive €20 in FREE credits : hetzner.cloud/...
Then configure postfix by calling
$ sudo nano /etc/postfix/main.cf
scroll to the bottom, and change 'inet_interfaces = all' to 'inet_interfaces = loopback-only'
see more postfix config options at
www.postfix.org...
restart postfix
$ sudo systemctl restart postfix
try sending an email form the command line,
$ echo "This is the body" | mail -s "This is the subject" -a "FROM:[senders address]" [your personal email]
That's it,
If you have nodejs, python, java, .net or any applications that need to send emails, you can now use the local smtp server you just created. Expect all incoming emails to be in your spam folder first until you white list them on your email client.