SMTP AUTH NTLM fail

 According normal SMTP protocal handshake step

You type

 >EHLO test.com

Server should reply  

 250-exch-cli-66 Hello [127.0.0.1]
 250-AUTH GSSAPI NTLM
 250-TURN
 250-SIZE 2097152
 250-ETRN
 250-PIPELINING
 250-DSN
 250-ENHANCEDSTATUSCODES
 250-8bitmime
 250-BINARYMIME
 250-CHUNKING
 250-VRFY
 250 OK

Client side 

>AUTH NTLM 

Server reply 

334 ntlm supported

https://docs.microsoft.com/en-us/openspecs/windows_protocols/ms-smtpntlm/a048c79f-7597-401b-bcb4-521d682de765

but if the server reject NTLM v1 , some legacy application will fail, server log will have "

Inbound Negotiate Failed because of unsupported

 

for example, library it doesn't support NTLM v2

Java : Javamail 

R: mailr

https://stackoverflow.com/questions/4337812/javamail-ntlm-authentication-failure 

因為有些舊的程式不支援NTLMv2 , 而在exchange 服务器又設定了拒絶NTLMv1 .

當進行SMTP 認證時會出現

Inbound Negotiate Failed because of unsupported