(based off of these directions):

sudo apt install -y postfix
sudo cp /usr/share/postfix/main.cf.debian /etc/postfix/main.cf
sudo postconf -e "relayhost = [email-smtp.us-west-2.amazonaws.com]:2587" "smtp_sasl_auth_enable = yes" "smtp_sasl_security_options = noanonymous" "smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd" "smtp_use_tls = yes" "smtp_tls_security_level = encrypt" "smtp_tls_note_starttls_offer = yes"
sudo sh -c 'echo [email-smtp.us-west-2.amazonaws.com]:2587 AWSUSER:AWSPASS > /etc/postfix/sasl_passwd'
sudo postmap hash:/etc/postfix/sasl_passwd
sudo chown root:root /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
sudo chmod 0600 /etc/postfix/sasl_passwd /etc/postfix/sasl_passwd.db
sudo postconf -e 'smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt'
sudo cp /etc/resolv.conf /var/spool/postfix/etc/resolv.conf # getting hostname unresolved without this. A bug in 14.04 that remains?
sudo sh -c 'echo inet_interfaces = loopback-only >> /etc/postfix/main.cf' # smtp accepted but only internally
sudo postfix stop; sudo postfix start; sudo postfix reload

from these directions execute as root:

echo "sender_canonical_classes = envelope_sender, header_sender" >> /etc/postfix/main.cf
echo "sender_canonical_maps =  regexp:/etc/postfix/sender_canonical_maps" >> /etc/postfix/main.cf
echo "smtp_header_checks = regexp:/etc/postfix/header_check" >> /etc/postfix/main.cf
echo "/.+/    NEWSENDER@ADDR.COM" > /etc/postfix/sender_canonical_maps
echo "/From:.*/ REPLACE From: NEWSENDER@ADDR.COM" >/etc/postfix/header_check
sudo postfix stop; sudo postfix start; sudo postfix reload

from https://serverfault.com/questions/147921/forcing-the-from-address-when-postfix-relays-over-smtp (example shown):

/etc/postfix/main.cf:
    smtp_generic_maps = hash:/etc/postfix/generic

/etc/postfix/generic:
    user@localdomain.local      account@isp.example.com
    @localdomain.local          wholedomain@isp.example.com
Then do:

sudo postmap /etc/postfix/generic
sudo /etc/init.d/postfix reload

• add root: <EMAILADDR> to /etc/aliases
• sudo newaliases

Test with sendmail:

sendmail -f sender@example.com recipient@example.com # -f allows you to specify from and is not required
From: Sender Name <sender@example.com>
Subject: Amazon SES Test                
This message was sent using Amazon SES.                
.

or test with telnet

• postfix should be set up with no configuration. When you do this, there are instructions given at the end to copy some sort of sample configuration.
• to reconfigure: sudo dpkg-reconfigure postfix
• to reload the settings: sudo postfix stop; sudo postfix start; sudo postfix reload
• when testing tail -f /var/log/mail.log is your friend
• view queued mail: postqueue -p
• flush queued mail: postqueue -f
• purge all queued mail: sudo postsuper -d ALL
• testing smtp connection and credentials from cli
  • port 465: swaks --to recipient@example.com --from sender@yourdomain.com --server smtp-server --port 465 --tls-on-connect --auth-user 'your_username' --auth-password 'your_password'
  • port 587: swaks --to recipient@example.com --from sender@yourdomain.com --server smtp-server --auth-user 'your_username' --auth-password 'your_password' -p 587 --tls
  • port 465 is legacy and 587 is the better choice for modern systems

• get current hostname: hostname
• set hostname with hostnamectl set-hostname <HOSTNAME>