What does an empty AUTH EHLO SMTP response mean with MS Exchange

exchangesmtpsmtp-auth

I'm a programmer, not a sys-admin, but my customer's sys-admins are not being helpful and after much googling I still can't find the answer to this.

My Java application gets the following response from my customer's MS Exchange following EHLO

EHLO PMNDEV3.prd.abc
250-PYTHON3.prd.abc Hello [155.5.200.100]
250-SIZE 20971520
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-AUTH
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250-XEXCH50
250 XSHADOW

Note that the 250-AUTH response has no parameters, so my software library (JavaMail) understandably says that it can't authenticate as there are no supported mechanisms advertised per RFC 4954

My question is why is this so? Is there perhaps some other non ESMTP authentication happening that is causing no AUTH mechanisms to be advertised?

Best Answer

The server's probably set up to not allow authentication over a plaintext connection.

What happens if you send AUTH PLAIN after the EHLO? Does it complain about AUTH PLAIN over a clear channel?

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