systemctl stop postfix

dnf install postfix s-nail cyrus-sasl-plain

Insert the following at the end of the /etc/postfix/main.cf file

smtpd_tls_auth_only = yes
smtpd_sasl_auth_enable = yes
smtpd_sasl_path = smtpd
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_tls_security_options = noanonymous
smtp_use_tls = yes
relayhost = [smtp.outlook.com]:587

Create the credentials file in /etc/postfix/sasl_passwd

vim /etc/postfix/sasl_passwd

use the following data

[smtp.outlook.com]:587 user@outlook.com:password

change the user to your user and password to your outlook password for that account in the information above

create the postmap file

postmap /etc/postfix/sasl_passwd

change permissions on the files

chmod 600 /etc/postfix/sasl_passwd
chmod 600 /etc/postfix/sasl_passwd.db