Hi, I'm using postfix to relay mail to Exchange 2010. Here is my config:

relayhost = [smtp.exchange.2010]
smtp_sasl_auth_enable = yes
smtp_sasl_password_maps = hash:/etc/postfix/relay_passwd
smtp_sasl_security_options =
#smtp_sasl_mechanism_filter = ntlm

(/etc/postfix/relay_passwd contains login information of some accounts on Exchange) With this configuration I can relay email to Exchange. The problem is: the message send from Postfix has header:

X-MS-Exchange-Organization-AuthAs: Anonymous

and the message is treated like unAuthenicated message on Exchange system (i.e when sending to distribution group require senders are authenicated, I received error: #550 5.7.1 RESOLVER.RST.AuthRequired; authentication required ##rfc822;[email protected]). I using Outlook with the same account as in Postfix and it can send without problem. The different I realized between two case is: Outlook send with NTLM auth mech, Postfix using LOGIN mech. Any idea?