#
# Postfix access control on HELO/EHLO context.
#
# References:
# * Postfix SMTP relay and access control
#   http://www.postfix.org/SMTPD_ACCESS_README.html
#
# NOTE: by default, patterns are case insensitive.
#
# Aaron LI
# 2017-08-05
#

#
# smtpd_helo_restrictions =
# 	permit_mynetworks,
# 	check_helo_access pcre:/usr/local/etc/postfix/helo-access.pcre,
# 	reject_non_fqdn_helo_hostname,
# 	reject_invalid_helo_hostname,
# 	reject_unknown_helo_hostname,
# 	permit
#

# Whitelist M$ Exchange Online Protection
# See also: https://technet.microsoft.com/en-us/library/dn163583
/^.*\.outbound.protection.outlook.com$/         OK