Using Postfix for this solution.

Follow instructions at https://www.linode.com/docs/guides/configure-postfix-to-send-mail-using-gmail-and-google-workspace-on-debian-or-ubuntu/

Or see the same at Sending Emails Using Postfix From Your Linux Server

• Will this also break with less sure apps?
  • The "Less Secure Apps" is not available in Gmail if your account is configured for 2-factor authentication
  • Everything should work OK.

For CENTOS8:

dnf install postfix ca-certificates mutt
dnf install cyrus-sasl, cyrus-sasl-gssapi, cyrus-sasl-lib, cyrus-sasl-plain
systemctl start postfix
systemctl enable postfix

Next perform the following steps as root:

cd /etc/postfix
cp main.cf main.cf.distro
mkdir /etc/postfix/sasl
cd /etc/postfix/sasl
vi sasl_passwd

Add this line:

[smtp.gmail.com]:587 [email protected]:password

postmap /etc/postfix/sasl/sasl_passwd
chown root:root /etc/postfix/sasl/sasl_passwd /etc/postfix/sasl/sasl_passwd.db
chmod 0600 /etc/postfix/sasl/sasl_passwd /etc/postfix/sasl/sasl_passwd.db

vi /etc/postfix/main.cf

Comment out this line:

#smtp_tls_security_level = may

Now wdd to the end of the main.cf file:

# Local Edits
relayhost = [smtp.gmail.com]:587
# Enable SASL authentication
smtp_sasl_auth_enable = yes
# Disallow methods that allow anonymous authentication
smtp_sasl_security_options = noanonymous
# Location of sasl_passwd
smtp_sasl_password_maps = hash:/etc/postfix/sasl/sasl_passwd
# Enable STARTTLS encryption
smtp_tls_security_level = encrypt
# Location of CA certificates
smtp_tls_CAfile = /etc/pki/tls/certs/ca-bundle.crt

Restart postfix:

systemctl restart postfix

Send test message:

mutt -s "Test" [email protected] </dev/null