AUTH NTLM with Exchange Server 2016 Problem

Help
1

Hello,

for some reason I’d like to use SMTP authentication with an internal SMTP-Gateway, which is a Exchange 2016.

However, the server replies with a

535 5.7 . 3 Authentication unsuccessful

(The username/credentials are double checked).

My Libre server is using this NTLM Negotiation Message (from what a tcpdump told me):

AUTH NTLM TlRMTVNTUAABAAAABzIAAAAAAAAgAAAAAAAAACAAAAA=

So far I have debugged, that a NTML Negotiation Message of (SMTP embedded)
AUTH NTLM TlRMTVNTUAABAAAAt4II4gAAAAAAAAAAAAAAAAAAAAAFAs4OAAAADw==
or
AUTH NTLM TlRMTVNTUAABAAAABzIAAAYABgArAAAACwALACAAAABXT1JLU1RBVElPTkRPTUFJTg==

would work, because the Exchange server would reply with a
SMTP 334 containing the NTLM challenge message.

(When base64-decoding, all these strings begin with “NTLMSSP”… which seems pretty OK…)

I guess that the code for this NTML authentication is not LibeNMS, but the laravel framework…

However, is there somebody who can give me a hint how to change this behavior or where to adress it to?
Is there somebody who can confirm that NTML is working/not working with Exchange 2016?

(Yes, I do agree that I sould look into the Exchange logs… but there’s no way for me to do so…)

Thanks a lot for your help!

Best regards,
-awaum