What is SMTP AUTH NTLM?

What is SMTP AUTH NTLM?

The NT LAN Manager (NTLM) Authentication: Simple Mail Transfer Protocol (SMTP) Extension specifies how an SMTP client and SMTP server can use the NTLM Authentication Protocol, as specified in [MS-NLMP], so that the SMTP server can authenticate the SMTP client.

How does SMTP AUTH work?

SMTP Authentication is the mechanism by which the clients of an ISP identify themselves to the mail server through which they intend to send email. It is not possible for any person to send email via any mail server they choose; mail servers will only allow the sending of email by legitimate users.

What is SMTP AUTH failure?

The “SMTP error 535 authentication failed” message may occur if you mistakenly enter the wrong username or password into your program. Usually, everyone uses the same username and password as your email address to log in to your mail server.

What is SMTP AUTH extension?

SMTP Authentication, often abbreviated SMTP AUTH, is an extension of the Simple Mail Transfer Protocol (SMTP) whereby a client may log in using any authentication mechanism supported by the server. It is mainly used by submission servers, where authentication is mandatory.

How to test authentication of SMTP with NTLM 250 authentication?

Take note of the line that reads ‘250-AUTH NTLM LOGIN’. If you want to test authenticated SMTP, you need to have the ‘AUTH LOGIN’ command available.

Is NTLM available in GSSAPI?

Though there is NTLM present but not used by server. In later cases, AUTH mechanism supported is only NTLM, so it’s failing (AUTH GSSAPI also fails). So you are landing into same issue what I am facing.

Why Auth GSSAPI is not working?

First case is successful due to LOGIN AUTH mechanism supported by server. Though there is NTLM present but not used by server. In later cases, AUTH mechanism supported is only NTLM, so it’s failing (AUTH GSSAPI also fails). So you are landing into same issue what I am facing.

What is unrecognized authentication type (NTLM)?

“5.7.4 Unrecognized authentication type” is an error code from the SMTP server. I would need to see the protocol logs to have a better idea of what is going on. If you say that NTLM is listed in the AuthenticationMechanisms, then it sounds like there is a bug in the server.