How to configure Postfix client relay to Exchange 2010 server

exchange-2010postfix

I'm getting 

(delivery temporarily suspended: SASL authentication failed; server myserver.com[xxx.xxx.xxx.x] said: 535 5.7.3 Authentication unsuccessful)

when I try to relay mail from Postfix 2.5.5-1.1 on Debian Lenny box to Exchange 2010.

I think I tried all possible combinations but I'm definitely missing something. Here is relevant part of main.cf:

broken_sasl_auth_clients = yes
smtp_sasl_auth_enable = yes
smtp_sasl_security_options = noanonymous
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd
smtp_pix_workarounds =
smtp_sasl_type = cyrus
smtp_always_send_ehlo = yes
relayhost = myserver.com

And I got libsasl2-modules installed. Anybody managed to successfully relay mail between Postfix and Exchange? Oh, and I already double-checked if password is right.

Best Answer

The Exchange Server will offer GSSAPI (Kerberos) but it seems that Cyrus SASL providing authentication service to Postfix was not configured to handle GSSAPI.

man 5 postconf | less +/^smtp_sasl_mechanism_filter

this will tell you what you need to set smtp_sasl_mechanism_filter to in order to get this to authenticate properly.

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