zimbra smtp relay authentication with multiple domains
zmprov ms `zmhostname` zimbraMtaSmtpSaslPasswordMaps "lmdb:/opt/zimbra/conf/relay_password"
zmprov ms `zmhostname` zimbraMtaSmtpSaslAuthEnable yes
zmprov ms `zmhostname` zimbraMtaSmtpCnameOverridesServername no
zmprov ms `zmhostname` zimbraMtaSmtpSaslSecurityOptions "noanonymous"
zmprov ms `zmhostname` zimbraMtaSmtpSaslMechanismFilter "plain,login"
zmprov ms `zmhostname` zimbraMtaSmtpTlsSecurityLevel may