Postfix: SASL authentication failed (Ubuntu 14.04 / Office365)

I’m unable to get postfix to work with our office 365 mail.

here’s the main.cf file:

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

append_dot_mydomain = no

readme_directory = no

smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
smtpd_use_tls=yes
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache


smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = signa-01
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = signa.com, signa-01, localhost.localdomain, localhost
relayhost = [smtp.office365.com]:587
mynetworks = 127.0.0.0/
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = loopback-only
inet_protocols = all
smtp_use_tls = yes
smtp_always_send_ehlo = yes
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_sasl_security_options = noanonymous
smtp_sasl_tls_security_options = noanonymous
smtp_tls_security_level = encrypt
smtp_generic_maps = hash:/etc/postfix/generic
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
smtp_sasl_mechanism_filter = login

And here is the error from mail.log:

Jul 15 04:50:28 signa-01 postfix/smtp[29736]: 211B2184D2E: SASL authentication failed; server smtp.office365.com[132.245.73.194] said: 535 5.7.3 Authentication unsuccessful
Jul 15 04:50:28 signa-01 postfix/smtp[29736]: connect to smtp.office365.com[2a01:111:f400:5387::2]:587: Network is unreachable
Jul 15 04:50:28 signa-01 postfix/smtp[29736]: 211B2184D2E: to=<clgsplace@gmail.com>, relay=none, delay=13, delays=0.02/0.02/13/0, dsn=4.4.1, status=deferred (connect to smtp.office365.com[2a01:111:f400:5387::2]:587: Network is unreachable)

Things I’ve done:

• I used this tutorial to configure postfix with 365
• I’ve verified the username and password are correct in /sasl_passwd
• I’ve tried adding smtp_sasl_mechanism_filter = login to main.cf

How can I troubleshoot this?