relayhost = [smtp.office365.com]:587
smtp_always_send_ehlo = yes
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_generic_maps = hash:/etc/postfix/generic
smtp_tls_security_level = may
smtp_sasl_security_options = noanonymous

/.*/    <o365 email>
root@server.difan.local <o365 email>
root@localdomain        <o365 email>
@localdomain            <o365 email>

[smtp.office365.com]:587 <o365 email>:<o365 password>

echo "This is the body of the email" | mail -s "This is the subject line"   difan.zhao@outlook.com

Mar 26 10:46:00 server postfix/pickup[1921]: 5DC594087202: uid=0 from=<root>
Mar 26 10:46:00 server postfix/cleanup[2495]: 5DC594087202: message-id=<20170326164600.5DC594087202@server.difan.local>
Mar 26 10:46:00 server postfix/qmgr[1922]: 5DC594087202: from=<root@server.difan.local>, size=486, nrcpt=1 (queue active)
Mar 26 10:46:00 server postfix/smtp[2497]: warning: SASL authentication failure: No worthy mechs found
Mar 26 10:46:00 server postfix/smtp[2497]: 5DC594087202: SASL authentication failed; cannot authenticate to server smtp.office365.com[40.97.128.34]: no mechanism available
... <last two messages repeated 4 times>
Mar 26 10:46:02 server postfix/smtp[2497]: 5DC594087202: to=<difan.zhao@outlook.com>, relay=smtp.office365.com[40.97.142.194]:587, delay=2.2, delays=0.02/0/2.2/0, dsn=4.7.0, status=deferred (SASL authentication failed; cannot authenticate to server smtp.office365.com[40.97.142.194]: no mechanism available)

/.*/    email@domain.com

sudo postmap hash:/etc/postfix/generic
sudo chown root:root /etc/postfix/generic /etc/postfix/generic.db
sudo chmod 644 /etc/postfix/generic /etc/postfix/generic.db